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{{Infobox OS
| name                   = Android
| title                  = Android
| logo                   = [[File:Android robot.svg|100px]]<br>[[File:Android.svg|200px]]
| screenshot             = [[File:Android 4.2 on the Nexus 4.png|200px]]
| caption                = Android 4.2 "Jelly Bean" on the [[Nexus 4]]
| developer              = [[Google]]<br>[[Open Handset Alliance]]<br>Android Open Source Project
| family                 = [[Unix-like]]
| working state          = Current
| source model           = [[Open-source software|Open source]]<ref name="philosophy">{{cite web |url=http://source.android.com/about/philosophy.html |title=Philosophy and Goals |work=Android Open Source Project |publisher=Google |accessdate=2012-04-21}}</ref>
| released               = {{start date|2008|9|23}}<ref>{{cite web|url=http://android-developers.blogspot.in/2008/09/announcing-android-10-sdk-release-1.html|title=Announcing the Android 1.0 SDK, release 1 |date=2008-09-23 |accessdate=2012-09-21}}</ref>
| latest release version = [[Android version history|4.2.1 ''Jelly Bean'']]
| latest release date    = {{release date and age|2012|11|27}}<ref>{{cite web|url=https://groups.google.com/forum/?fromgroups=#!topic/android-building/s-qNo2fxeHY |title=&#91;Android 4.2.1 hits AOSP&#93; 4.2.1 in AOSP |date=2012-11-27 |accessdate=2012-11-27}}</ref><ref>{{cite web|url=http://androidcommunity.com/android-4-2-1-jelly-bean-heads-to-aosp-20121127/ |title=Android 4.2.1 Jelly Bean heads to AOSP |publisher=Android Community |date= |accessdate=2012-11-27}}</ref>
| frequently updated     = yes
| marketing target       = [[Smartphone]]s<br>[[Tablet computer]]s
| programmed in          = [[C (programming language)|C]], [[C++]], [[Java (programming language)|Java]]<ref>{{cite web |title=Android Code Analysis|url=http://www.ohloh.net/p/android/analyses/latest |accessdate=2012-06-01}}</ref>
| language               = Multi-lingual
| package manager        = [[Google Play]], [[APK (file format)|APK]]
| supported platforms    = [[ARM architecture|ARM]], [[MIPS architecture|MIPS]],<ref>{{cite web |url=http://www.eetimes.com/electronics-news/4215490/MIPS-gets-sweet-with-Honeycomb |title=MIPS gets sweet with Honeycomb |publisher=Eetimes.com |date= |accessdate=2012-02-20}}</ref> [[x86]]<ref name="ARMAN-4.0-on-x86" />
| kernel type            = [[Monolithic kernel|Monolithic]] ([[Android (operating system)#Linux|modified Linux kernel]])
| ui                     = [[Graphical user interface|Graphical]] ([[Multi-touch]])
| license                = [[Apache License]] 2.0<br>[[Linux kernel]] patches under [[GNU General Public License|GNU GPL]] v2<ref name="Licenses"/>
| website                = {{URL|http://www.android.com/}}
}}
'''Android''' is a [[Linux]]-based [[mobile operating system|operating system]] designed primarily for [[touchscreen]] mobile devices such as [[smartphone]]s and [[tablet computer]]s. Initially developed by Android, Inc., which [[Google]] backed financially and later purchased in 2005,<ref name="AndroidInc">{{cite web |url=http://www.businessweek.com/technology/content/aug2005/tc20050817_0949_tc024.htm |title=Google Buys Android for Its Mobile Arsenal |last=Elgin |first=Ben |date=August 17, 2005 |work=Bloomberg Businessweek |publisher=Bloomberg |archiveurl=http://www.webcitation.org/5wk7sIvVb |archivedate=February 24, 2011 |accessdate=2012-02-20 |quote=In what could be a key move in its nascent wireless strategy, Google (GOOG) has quietly acquired startup Android, Inc.,&nbsp;...}}</ref> Android was unveiled in 2007 along with the founding of the [[Open Handset Alliance]]: a consortium of [[computer hardware|hardware]], [[software]], and [[telecommunication]] companies devoted to advancing [[open standard]]s for mobile devices.<ref name="AndroidAnnouncement">{{cite press release |url=http://www.openhandsetalliance.com/press_110507.html |title=Industry Leaders Announce Open Platform for Mobile Devices |publisher=[[Open Handset Alliance]] |date=November 5, 2007 |accessdate=2012-02-17}}</ref> The first Android-powered phone was sold in October 2008.<ref>{{cite web|title=T-Mobile G1 Spec|url=http://www.gsmarena.com/t_mobile_g1-2533.php|work=Infosite and comparisons|publisher=GSM Arena|accessdate=12 September 2012}}</ref>

Android is [[open source]] and Google releases the code under the [[Apache License]].<ref name="AndroidOverview">{{cite web |url=http://www.openhandsetalliance.com/android_overview.html |publisher=Open Handset Alliance |title=Android Overview |accessdate=2012-02-15}}</ref> This open source code and permissive licensing allows the software to be freely modified and distributed by device manufacturers, wireless carriers and enthusiast developers. Additionally, Android has a large community of developers writing applications ("[[Mobile app|apps]]") that extend the functionality of devices, written primarily in a customized version of the [[Java (programming language)|Java]] programming language.<ref>{{cite news |url=http://news.cnet.com/8301-13580_3-9815495-39.html |title=Google's Android parts ways with Java industry group |work=[[CNET News]] |first=Stephen |last=Shankland |date=November 12, 2007 |accessdate=2012-02-15}}</ref> In October 2012, there were approximately 700,000 apps available for Android, and the estimated number of applications downloaded from [[Google Play]], Android's primary app store, was 25 billion.<ref name="appstats-700000">{{cite web |url=http://www.tomsguide.com/us/Google-Play-Android-Apple-iOS,news-16235.html |title=Google Play Matches Apple's iOS With 700,000 Apps}}</ref><ref name="appstats-25billion".>{{cite web |url=http://officialandroid.blogspot.ca/2012/09/google-play-hits-25-billion-downloads.html |title=Google Play hits 25 billion downloads &#124; Official Android Blog}}</ref>

These factors have allowed Android to become the world's most widely used smartphone platform<ref name="canalysQ42010">{{cite web |url=http://www.canalys.com/newsroom/google%E2%80%99s-android-becomes-world%E2%80%99s-leading-smart-phone-platform |title=Google's Android becomes the world's leading smart phone platform |work=Canalys |date=January 31, 2011 |accessdate=2012-02-15}}</ref> and the software of choice for technology companies who require a low-cost, customizable, lightweight operating system for [[high tech]] devices without developing one from scratch.<ref name=ars5th /> As a result, despite being primarily designed for phones and tablets, it has seen additional applications on [[television]]s, [[games console]]s and other electronics. Android's open nature has further encouraged a large community of developers and enthusiasts to use the open source code as a foundation for community-driven projects, which add new features for advanced users<ref name=apolroms /> or bring Android to devices which were officially released running other operating systems.

Android had a worldwide smartphone market share of 75% during the third quarter of 2012,<ref name="idcQ3">{{cite web|url=http://www.idc.com/getdoc.jsp?containerId=prUS23771812 |title=Android Marks Fourth Anniversary Since Launch with 75.0% Market Share in Third Quarter, According to IDC - prUS23771812 |publisher=Idc.com |date= |accessdate=2012-11-03}}</ref> with 500 million devices activated in total and 1.3 million activations per day.<ref name="Google Team">{{cite web | title= 500 million devices activated globally, and over 1.3 million added every single day |publisher= official Android Engineering teams |date= 2012-09-12 |url= https://plus.google.com/u/0/110023707389740934545/posts/R5YdRRyeTHM }}</ref><ref name="Eric Schmidt">{{cite web | title= There Are Now 1.3 Million Android Device Activations Per Day |publisher= Techcrunch |date= 2012-09-05 |url= http://techcrunch.com/2012/09/05/eric-schmidt-there-are-now-1-3-million-android-device-activations-per-day/ }}</ref>

==History==
Android, Inc. was founded in [[Palo Alto, California]] in October 2003 by [[Andy Rubin]] (co-founder of [[Danger (company)|Danger]]),<ref name="AndyRubin">{{Cite news |url=http://www.nytimes.com/2007/11/04/technology/04google.html?_r=2&hp=&pagewanted=all |title=I, Robot: The Man Behind the Google Phone |last=Markoff |first=John |date=November 4, 2007 |work=The New York Times |accessdate=2012-02-15}}</ref> [[Rich Miner]] (co-founder of Wildfire Communications, Inc.),<ref name="autogenerated1">{{Cite news |url=http://www.boston.com/business/technology/articles/2007/09/02/introducing_the_google_phone/ |title=Introducing the Google Phone |first=Scott |last=Kirsner |work=[[The Boston Globe]] |date=September 2, 2007 |archiveurl=http://web.archive.org/web/20100104054533/http://www.boston.com/business/technology/articles/2007/09/02/introducing_the_google_phone/ |archivedate=January 4, 2010 |accessdate=2012-02-15}}</ref> Nick Sears<ref>{{Cite news | url=http://www.wired.com/magazine/2011/04/mf_android/all/1 | title=How the Android Ecosystem Threatens the iPhone | work=Wired | date=April 2011 | accessdate=June 2, 2012 | author=Vogelstein, Fred}}</ref> (once VP at [[T-Mobile USA|T-Mobile]]),<ref name="Nick">{{Cite press release |url=http://newsroom.t-mobile.com/articles/t-mobile-nokia-N-Gage |title=T-Mobile Brings Unlimited Multiplayer Gaming to US Market with First Launch of [[Nokia]] [[N-Gage (service)|N-Gage]] Game Deck |date=September 23, 2003 |publisher=T-Mobile |accessdate=2012-02-15}}</ref> and Chris White (headed design and interface development at [[WebTV]])<ref name="AndroidInc" /> to develop, in Rubin's words "smarter mobile devices that are more aware of its owner's location and preferences".<ref name="AndroidInc" /> Despite the past accomplishments of the founders and early employees, Android Inc. operated secretly, revealing only that it was working on software for mobile phones.<ref name="AndroidInc"/> That same year, Rubin ran out of money. [[Steve Perlman]], a close friend of Rubin, brought him $10,000 in cash in an envelope and refused a stake in the company.<ref name="StevePerlman">{{Cite web |url=http://www.businessweek.com/magazine/the-edison-of-silicon-valley-07272011.html |title=Steve Perlman's Wireless Fix |last=Vance |first=Ashlee |date=27 July 2011 |work=Bloomberg Businessweek |publisher=Bloomberg |accessdate=3 November 2012}}</ref>

[[Google]] acquired Android Inc. on August 17, 2005, making it a wholly owned subsidiary of Google. Key employees of Android Inc., including Rubin, Miner and White, stayed at the company after the acquisition.<ref name="AndroidInc" /> Not much was known about Android Inc. at the time, but many assumed that Google was planning to enter the [[mobile phone]] market with this move.<ref name="AndroidInc" /> At Google, the team led by Rubin developed a mobile device platform powered by the [[Linux kernel]]. Google marketed the platform to handset makers and [[Mobile network operator|carriers]] on the promise of providing a flexible, upgradable system. Google had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.<ref name="EngadgetMobileOS">{{cite web |url=http://www.engadget.com/2007/08/28/google-is-working-on-a-mobile-os-and-its-due-out-shortly |title=Google is working on a mobile OS, and it's due out shortly |last=Block |first=Ryan |work=[[Engadget]] |date=August 28, 2007 |accessdate=2012-02-17}}</ref><ref name="WSJ">{{cite news |url=http://online.wsj.com/article_email/SB118602176520985718-lMyQjAxMDE3ODA2MjAwMjIxWj.html |title=Google Pushes Tailored Phones To Win Lucrative Ad Market |last1=Sharma |first1=Amol |first2=Kevin J. |last2=Delaney |work=[[The Wall Street Journal]] |date=August 2, 2007 |accessdate=2012-02-17}}</ref><ref name="DT">{{cite web |archiveurl=http://web.archive.org/web/20070703031543/http://www.directtraffic.org/OnlineNews/Google_admits_to_mobile_phone_plan_18094880.html |archivedate=July 3, 2007 |url=http://www.directtraffic.org/OnlineNews/Google_admits_to_mobile_phone_plan_18094880.html |title=Google admits to mobile phone plan |work=directtraffic.org |publisher=Google News |date=March 20, 2007 |accessdate=2012-02-17}}</ref>

Speculation about Google's intention to enter the mobile communications market continued to build through December 2006.<ref name="McKay">{{Cite news |last=McKay |first=Martha |url=http://record-bergen.vlex.com/vid/iphone-phone-linksys-versatile-cordless-62885923 |title=Can iPhone become your phone?; Linksys introduces versatile line for cordless service |work=[[The Record (Bergen County)]] |page=L9 |date=December 21, 2006 |accessdate=2012-02-21 |quote=And don't hold your breath, but the same cell phone-obsessed tech watchers say it won't be long before Google jumps headfirst into the phone biz. Phone, anyone?}}</ref> Reports from the [[BBC]] and the ''[[Wall Street Journal]]'' noted that Google wanted its search and applications on mobile phones and it was working hard to deliver that. Print and online media outlets soon reported rumors that Google was developing a Google-branded [[Handset#Telephony|handset]]. Some speculated that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators. In September 2007, ''[[InformationWeek]]'' covered an [[Evalueserve]] study reporting that Google had filed several [[patent]] applications in the area of mobile telephony.<ref name="IWpatents">{{cite news |url=http://www.informationweek.com/news/showArticle.jhtml?articleID=201807587&cid=nl_IWK_daily |title=Google's Secret Patent Portfolio Predicts gPhone |last=Claburn |first=Thomas |work=[[InformationWeek]] |date=September 19, 2007 |accessdate=2012-02-17}}{{Dead link|date=June 2012}}</ref><ref name="MNpatents">{{Cite web |url=http://www.moconews.net/entry/419-googles-strong-mobile-related-patent-portfolio |title=Google's Strong Mobile-Related Patent Portfolio |last=Pearce |first=James Quintana |work=mocoNews.net |date=September 20, 2007 |accessdate=2012-02-17}}</ref>

On November 5, 2007, the [[Open Handset Alliance]], a [[consortium]] of technology companies including Google, device manufacturers such as [[HTC]] and [[Samsung]], wireless carriers such as [[Sprint Nextel]] and [[T-Mobile]], and chipset makers such as [[Qualcomm]] and [[Texas Instruments]], unveiled itself, with a goal to develop [[open standard]]s for mobile devices.<ref name="AndroidAnnouncement" /> That day, Android was unveiled as its first product, a mobile device [[platform (computing)|platform]] built on the [[Linux kernel]] version 2.6.<ref name="AndroidAnnouncement" /> The first commercially available phone to run Android was the [[HTC Dream]], released on October 22, 2008.<ref name="HTC">{{Cite news |publisher=HTC |url=http://www.htc.com/www/press.aspx?id=66338&lang=1033 |title=T-Mobile Unveils the T-Mobile G1 - the First Phone Powered by Android |date=September 23, 2008 |archiveurl=http://web.archive.org/web/20110712230204/http://www.htc.com/www/press.aspx?id=66338&lang=1033 |archivedate=July 12, 2011 |accessdate=2012-02-17}} AT&T's first device to run Android was the Motorola Backflip.</ref>

Since 2008, Android has seen [[Android version history|numerous updates]] which have incrementally improved the operating system, adding new features and fixing bugs in previous releases. Each major release is named in alphabetical order after a dessert or sugary treat; for example, version 1.5 ''Cupcake'' was followed by 1.6 ''Donut''. The latest release is 4.2 ''Jelly Bean''. In 2010, Google launched its [[Google Nexus|Nexus]] series of devices—a line of smartphones and tablets running the Android operating system, and built by a manufacturer partner. HTC collaborated with Google to release the first Nexus smartphone,<ref>{{Cite news |url=http://www.guardian.co.uk/technology/2010/mar/14/google-mobile-phone-launch-delay |title=Google forced to delay British launch of Nexus phone |publisher=guardian.co.uk |date=March 14, 2010 |author=Richard Wray |location=London |accessdate=2012-02-17}}</ref> the [[Nexus One]]. The series has since been updated with newer devices, such as the [[Nexus&nbsp;4]] phone and [[Nexus&nbsp;10]] tablet, made by [[LG]] and Samsung, respectively. Google releases the Nexus phones and tablets to act as their [[Flagship#Flagship as metaphor|flagship]] Android devices, demonstrating Android's latest software and hardware features.

==Description==

{{see also|List of features in Android|Android version history}}

===Interface===
Android's user interface is based on [[Direct manipulation interface|direct manipulation]],<ref name=touch>{{cite web|url=http://source.android.com/tech/input/touch-devices.html |title=Touch Devices &#124; Android Open Source |publisher=Source.android.com |date= |accessdate=2012-09-15}}</ref> using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching and reverse pinching to manipulate on-screen objects.<ref name=touch /> The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide [[haptic feedback]] to the user. Internal hardware such as [[accelerometers]], [[gyroscopes]] and [[proximity sensors]] are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a [[steering wheel]].<ref>{{cite web|url=http://phandroid.com/2011/12/22/real-racing-2-speeds-into-the-android-market-leaves-part-1-in-the-dust/ |title=Real Racing 2 Speeds Into The Android Market – Leaves Part 1 In The Dust |publisher=Phandroid.com |date=2011-12-22 |accessdate=2012-09-15}}</ref>

Android devices boot to the homescreen, the primary navigation and information point on the device, which is similar to the [[Desktop metaphor|desktop]] found on PCs. Android homescreens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content such as the weather forecast, the user's email inbox, or a [[news ticker]] directly on the homescreen.<ref>{{cite web|url=http://developer.android.com/design/patterns/widgets.html |title=Widgets &#124; Android Developers |publisher=Developer.android.com |date= |accessdate=2012-09-15}}</ref> A homescreen may be made up of several pages that the user can swipe back and forth between, though Android's homescreen interface is heavily customisable, allowing the user to adjust the look and feel of the device to their tastes. Third party apps available on [[Google Play]] and other app stores can extensively re-[[Theme (computing)|theme]] the homescreen, and even mimic the look of other operating systems, such as [[Windows Phone]].<ref>{{cite web|url=http://lifehacker.com/5804091/launcher-7-brings-windows-phones-simple-attractive-interface-to-android |title=Launcher 7 Brings Windows Phone's Simple, Attractive Interface to Android |publisher=Lifehacker.com |date=2011-05-20 |accessdate=2012-11-24}}</ref> Most manufacturers, and some wireless carriers, customise the look and feel of their Android devices to differentiate themselves from the competition.

Present along the top of the screen is a status bar, showing information about the device and its connectivity. This status bar can be "pulled" down to reveal a notification screen where apps display important information or updates, such as a newly received email or [[SMS]] text, in a way that doesn't immediately interrupt or inconvenience the user.<ref name=ui-overview>{{cite web|url=http://developer.android.com/design/get-started/ui-overview.html |title=UI Overview &#124; Android Developers |publisher=Developer.android.com |date= |accessdate=2012-09-15}}</ref> In early versions of Android these notifications could be tapped to open the relevant app, but recent updates have provided enhanced functionality, such as the ability to call a number back directly from the missed call notification without having to open the dialer app first.<ref name=notifications>{{cite web|url=http://developer.android.com/design/patterns/notifications.html |title=Notifications &#124; Android Developers |publisher=Developer.android.com |date= |accessdate=2012-09-15}}</ref> Notifications are persistent until read or dismissed by the user.

===Applications===
[[File:Play Store app.png|thumb|150px|left|upright|Play Store on the [[Galaxy Nexus]].]]
{{see also|Android software development|Google Play}}
Android has a growing selection of third party applications, which can be acquired by users either through an app store such as [[Google Play]] or the [[Amazon Appstore]], or by downloading and installing the application's [[APK (file format)|APK]] file from a third-party site.<ref name="wired_alt_app_stores">{{cite web |url=http://www.wired.com/gadgetlab/2010/06/independent-app-stores-take-on-googles-android-market/ |title=Independent App Stores Take On Google's Android Market |date=June 11, 2010 |first=Priya |last=Ganapati |publisher=[[Wired News]] |accessdate=2012-02-20}}</ref> The Play Store application allows users to browse, download and update apps published by Google and third-party developers, and is pre-installed on devices that comply with Google's compatibility requirements.<ref>{{cite web |url= http://source.android.com/compatibility/index.html |title=Android Compatibility |work=Android Open Source Project |accessdate=2012-02-20}}</ref> The app filters the list of available applications to those that are compatible with the user's device, and developers may restrict their applications to particular carriers or countries for business reasons.<ref>{{cite web |url=http://developer.android.com/guide/practices/compatibility.html |title=Android Compatibility |work=Android Developers |accessdate=2012-02-20}}</ref> Purchases of unwanted applications can be refunded within 15 minutes of the time of download,<ref name="support.google returning apps">{{cite web |url=https://support.google.com/androidmarket/bin/answer.py?hl=en&answer=134336&topic=1046718&ctx=topic |title=Returning Apps |publisher=[[Google]] |accessdate= 9 January 2012}}</ref> and some carriers offer direct carrier billing for Google Play application purchases, where the cost of the application is added to the user's monthly bill.<ref>{{cite web |url=http://android-developers.blogspot.com/2011/04/new-carrier-billing-options-on-android.html |title=Android Developers Blog: New Carrier Billing Options on Android Market |last=Chu |first=Eric | publisher =android-developers.blogspot.com |date=13 April 2011|accessdate=15 May 2011}}</ref> As of September 2012, there were more than 675,000 apps available for Android, and the estimated number of applications downloaded from the Play Store was 25 billion.<ref name="appstats-25-billion">{{cite web |url=http://officialandroid.blogspot.com/2012/09/google-play-hits-25-billion-downloads.html |title=Google Play hits 25 Billion downloads, 675,000 apps and games}}</ref> 

Applications are developed in the [[Java (programming language)|Java]] language using the [[Android SDK|Android software development kit]] (SDK). The SDK includes a comprehensive set of development tools,<ref>{{cite web |url = http://developer.android.com/guide/developing/tools/index.html |title = Tools Overview |work = Android Developers |date = 21 July 2009}}</ref>  including a [[debugger]], [[Software library|software libraries]], a handset [[emulator]] based on [[QEMU]], documentation, sample code, and tutorials. The officially supported [[integrated development environment]] (IDE) is [[Eclipse (software)|Eclipse]] using the Android Development Tools (ADT) plugin. Other development tools are available, including a [[Android NDK|Native Development Kit]] for applications or extensions in C or C++, [[Google App Inventor]], a visual environment for novice programmers, and various [[Multiple phone web based application framework|cross platform mobile web applications frameworks]].

In order to work around limitations on reaching Google services due to [[Internet censorship in the People's Republic of China]], Android devices sold in the PRC are generally customized to use state approved services instead.<ref>Yun Qing, Liau. [http://www.zdnet.com/cn/phonemakers-make-android-china-friendly-7000005679/ "Phonemakers make Android China-friendly."] ''ZD Net'', 15 October 2012.</ref>
{{-}}

==Development==

Android is developed in private by Google until the latest changes and updates are ready to be released, at which point the source code is made available publicly.<ref>At http://source.android.com</ref> This source code will only run without modification on select devices, usually the [[Google Nexus|Nexus]] series of devices.<ref>{{cite web|author=John McCann&nbsp; |url=http://www.techradar.com/news/phone-and-communications/mobile-phones/android-4-1-jelly-bean-source-code-released-1088404 |title=Android 4.1 Jelly Bean source code released &#124; News |publisher=TechRadar |date=2012-12-13 |accessdate=2012-12-20}}</ref> With many devices, there are proprietary components which have to be provided by the manufacturer, in order for Android to work.<ref>{{Cite web| title = Building for devices |work = Android Open Source Project |accessdate = 2012-12-20 |url = http://source.android.com/source/building-devices.html}}</ref>

===Linux===
[[File:Android-System-Architecture.svg|thumb|right|Architecture diagram]]
Android consists of a [[Kernel (software)|kernel]] based on [[Linux kernel]] version 2.6 and, from Android 4.0 ''Ice Cream Sandwich'' onwards, version 3.x, with [[middleware]], [[software library|libraries]] and [[Application programming interface|APIs]] written in [[C (programming language)|C]], and [[application software]] running on an [[application framework]] which includes Java-compatible libraries based on [[Apache Harmony]]. Android uses the [[Dalvik (software)|Dalvik virtual machine]] with [[just-in-time compilation]] to run Dalvik 'dex-code' (Dalvik Executable), which is usually translated from [[Java bytecode]].<ref>{{cite web |url=http://www.tbray.org/ongoing/When/201x/2010/11/14/What-Android-Is |title=What Android Is |author=Tim Bray |work=ongoing by Tim Bray |date=November 24, 2010 |accessdate=2012-02-15}}</ref> The main hardware platform for Android is the [[ARM architecture]]. There is support for [[x86]] from the [[Android x86]] project,<ref name="ARMAN-4.0-on-x86">{{cite web |url=http://www.computerworld.com/s/article/9222323/Google_s_Android_4.0_ported_to_x86_processors |title=Google's Android 4.0 ported to x86 processors |last=Shah |first=Agam |date=December 1, 2011 |work=Computerworld |publisher=International Data Group |accessdate=2012-02-20}}</ref> and [[Google TV]] uses a special x86 version of Android.

Android's linux kernel has further architecture changes by Google outside the typical Linux kernel development cycle.<ref>{{cite video |url=http://www.youtube.com/watch?v=QBGfUs9mQYY |title= Androidology – Part 1 of 3 – Architecture Overview |medium=Video |publisher=[[YouTube]] |date=September 6, 2008 |accessdate=2007-11-07}}</ref> Android does not have a native [[X Window System]] by default nor does it support the full set of standard [[GNU]] libraries, and this makes it difficult to port existing Linux applications or libraries to Android.<ref>{{cite web |url=http://arstechnica.com/open-source/reviews/2009/02/an-introduction-to-google-android-for-developers.ars |title=Dream(sheep++): A developer's introduction to Google Android |date=February 23, 2009 |last=Paul |first=Ryan |work=[[Ars Technica]] |accessdate=2012-02-15}}</ref> Support for simple C and [[Simple DirectMedia Layer|SDL]] applications is possible by injection of a small Java [[shim (computing)|shim]] and usage of the [[JNI]]<ref name="sdlandroid">{{cite web|url=http://www.libsdl.org/tmp/SDL/README.android |title=Simple DirectMedia Layer for Android |quote=''How the port works, - Android applications are Java-based, optionally with parts written in C, - As SDL apps are C-based, we use a small Java shim that uses JNI to talk to the SDL library, - This means that your application C code must be placed inside an android Java project, along with some C support code that communicates with Java, - This eventually produces a standard Android .apk package''|date=2012-08-12|accessdate=2012-09-09 |publisher=sdl.org}}</ref> like, for example, in the [[Jagged Alliance 2]] port for Android.<ref name="ja2forandroid">[http://www.ja-galaxy-forum.com/board/ubbthreads.php?ubb=showflat&Number=273148&page=1 JA2 Stracciatella Feedback » Jagged Alliance 2 Android Stracciatella Port RC2 Release - please test] on the Bear's Pit Forum, October 3, 2011</ref>

Certain features that Google contributed back to the Linux kernel, notably a power management feature called wakelocks, were rejected by mainline kernel developers, partly because kernel maintainers felt that Google did not show any intent to maintain their own code.<ref name="hartmann2">{{cite web |url=http://www.zdnet.com/news/linux-developer-explains-android-kernel-code-removal/389733 |title=Linux developer explains Android kernel code removal |author=David Meyer |date=February 3, 2010 |publisher=[[ZDNet]] |accessdate=2012-02-20}}</ref><ref name="hartmann">{{cite web |url=http://www.kroah.com/log/linux/android-kernel-problems.html |title=Android and the Linux kernel community |author=[[Greg Kroah-Hartman]] |date=February 2, 2010 |accessdate=2012-02-20 |quote=''Google shows no sign of working to get their code upstream anymore. Some companies are trying to strip the Android-specific interfaces from their codebase and push that upstream, but that causes a much larger engineering effort, and is a pain that just should not be necessary.''}}</ref><ref>{{cite web |url=https://www.linux.com/news/embedded-mobile/mobile-linux/344486-garretta-linuxcon-talk-emphasizes-lessons-learned-from-androidkernel-saga |title=Garrett's LinuxCon Talk Emphasizes Lessons Learned from Android/Kernel Saga |author=Brian Proffitt |date=August 10, 2010 |publisher=[[Linux.com]] |accessdate=2012-02-21}}</ref> Google announced in April 2010 that they would hire two employees to work with the Linux kernel community,<ref>{{cite web |url=http://www.zdnet.com/blog/open-source/dibona-google-will-hire-two-android-coders-to-work-with-kernelorg/6274 |title=DiBona: Google will hire two Android coders to work with kernel.org |work=www.zdnet.com |author=Brian Proffitt  |date=April 15, 2010 |accessdate=2012-02-20}}</ref> but [[Greg Kroah-Hartman]], the current Linux kernel maintainer for the stable branch, said in December 2010 that he was concerned that Google was no longer trying to get their code changes included in mainstream Linux.<ref name="hartmann"/> Some Google Android developers hinted that "the Android team was getting fed up with the process," because they were a small team and had more urgent work to do on Android.<ref>{{cite web |url=http://blogs.computerworld.com/16900/android_linux_kernel_fight_continues |title=Android/Linux kernel fight continues |publisher=[[Computerworld]] |author=Steven J. Vaughan-Nichols |date=September 7, 2010 |accessdate=2012-02-20}}</ref>

In August 2011, [[Linus Torvalds]] said that "eventually Android and Linux would come back to a common kernel, but it will probably not be for four to five years".<ref>{{cite web |url=http://www.zdnet.com/blog/open-source/linus-torvalds-on-android-the-linux-fork/9426 |title=Linus Torvalds on Android, the Linux fork |author=Steven J. Vaughan-Nichols |work=zdnet.com |date=August 18, 2011 |accessdate=2012-02-15}}</ref> In December 2011, [[Greg Kroah-Hartman]] announced the start of the Android Mainlining Project, which aims to put some Android [[Device driver|drivers]], patches and features back into the Linux kernel, starting in Linux 3.3.<ref>{{cite web |url=http://www.h-online.com/open/news/item/Android-drivers-to-be-included-in-Linux-3-3-kernel-1400996.html |title=Android drivers to be included in Linux 3.3 kernel |author=Chris von Eitzen |work=h-online.com |date=December 23, 2011 |accessdate=2012-02-15}}</ref> Linux included the autosleep and wakelocks capabilities in the 3.5 kernel, after many previous attempts at merger. The interfaces are the same but the upstream Linux implementation allows for two different suspend modes: to memory (the traditional suspend that Android uses), and to disk (hibernate, as it is known on the desktop).<ref>{{cite web|last=Jonathan|first=Corbet|title=Autosleep and wakelocks|url=https://lwn.net/Articles/479841/|publisher=LWN}}</ref>

The [[flash storage]] on Android devices is split into several partitions, such as "/system" for the operating system itself and "/data" for user data and app installations.<ref>{{cite web|last=Raja |first=Haroon Q. |url=http://www.addictivetips.com/mobile/android-partitions-explained-boot-system-recovery-data-cache-misc/ |title=Android Partitions Explained: boot, system, recovery, data, cache & misc |publisher=Addictivetips.com |date=2011-05-19 |accessdate=2012-09-15}}</ref> In contrast to desktop Linux distributions, Android device owners are not given [[Superuser|root]] access to the operating system and sensitive partitions such as /system are [[Read-only memory|read-only]]. However, root access can be obtained by exploiting [[Vulnerability (computing)|security flaws]] in Android, which is used frequently by the [[#Open source community|open source community]] to enhance the capabilities of their devices,<ref>See [[Android rooting|rooting]]</ref> but also by malicious parties to install [[computer virus|viruses]] and [[malware]].<ref>{{cite web |author=Jools Whitehorn&nbsp; |url=http://www.techradar.com/news/phone-and-communications/mobile-phones/android-malware-gives-itself-root-access-1062294 |title=Android malware gives itself root access &#124; News |publisher=TechRadar |date= |accessdate=2012-09-15}}</ref>

===Memory management===

Since Android devices are usually battery-powered, Android is designed to manage memory ([[Random-access memory|RAM]]) to keep power consumption at a minimum, in contrast to desktop operating systems which generally assume they are connected to unlimited [[mains electricity]]. When an Android app is no longer in use, the system will automatically suspend it in memory - while the app is still technically "open," suspended apps consume no resources (e.g. battery power or processing power) and sit idly in the background until needed again. This has the dual benefit of increasing the general responsiveness of Android devices, since apps don't need to be closed and reopened from scratch each time, but also ensuring background apps don't waste power needlessly.<ref name=phonedogtask>{{cite web|url=http://www.phonedog.com/2011/06/26/the-truth-about-android-task-killers-and-why-you-don-t-need-them/ |title=The truth about Android task killers and why you don't need them |publisher=PhoneDog |date=2011-06-26 |accessdate=2012-10-30}}</ref>

Android manages the apps stored in memory automatically: when memory is low, the system will begin killing apps and processes that have been inactive for a while, in reverse order since they were last used (i.e. oldest first). This process is designed to be invisible to the user, such that users do not need to manage memory or the killing of apps themselves.<ref name=phandroidtask>{{cite web|url=http://phandroid.com/2011/06/16/android-psa-stop-using-task-killer-apps-now/ |title=Android PSA: Stop Using Task Killer Apps |publisher=Phandroid.com |date=2011-06-16 |accessdate=2012-10-30}}</ref> However, confusion over Android memory management has resulted in third-party task killers becoming popular on the [[Google Play]] store; these third-party task killers are generally regarded as doing more harm than good.<ref name=lifehackertask>{{cite web|url=http://lifehacker.com/5862994/real-world-test-show-that-android-task-killers-are-still-useless |title=Updates |publisher=Lifehacker.com |date= |accessdate=2012-11-02}}</ref>

=== Update schedule ===
[[File:G1, Nexus One, Nexus S, Galaxy Nexus.jpg|thumb|left|From left to right: [[HTC Dream|HTC Dream (G1)]], [[Nexus One]], [[Nexus S]], [[Galaxy Nexus]]|200px]]
{{see also|Android version history}}
Google provides major updates, incremental in nature, to Android every six to nine months, which most devices are capable of receiving [[Over-the-air programming|over the air]].<ref>{{cite web|last=Isacc |first=Mike |url=http://arstechnica.com/gadgets/2011/10/a-deep-dive-tour-of-ice-cream-sandwich-with-androids-chief-engineer/ |title=A deep-dive tour of Ice Cream Sandwich with Android's chief engineer |publisher=Ars Technica |date=2011-10-21 |accessdate=2012-09-15}}</ref> The latest major update is Android 4.2 ''Jelly Bean''.<ref>{{cite web|url=http://googleblog.blogspot.de/2012/10/nexus-best-of-google-now-in-three-sizes.html|title=Nexus: The best of Google, now in three sizes|last=Rubin|first=Andy|date=October 29, 2012|publisher=Official Google Blog|accessdate=29 October 2012}}</ref>

Compared to its chief rival mobile operating system, namely [[iOS]], Android updates are typically slow to reach actual devices. For devices not under the [[Google Nexus|Nexus]] brand, updates often arrive months from the time the given version is officially released.<ref name=alliance>{{cite web|last=Cunningham |first=Andrew |url=http://arstechnica.com/gadgets/2012/06/what-happened-to-the-android-update-alliance/ |title=What happened to the Android Update Alliance? |publisher=Ars Technica |date=2012-06-27 |accessdate=2012-09-15}}</ref> This is caused partly due to the extensive variation in [[Computer hardware|hardware]] of Android devices, to which each update must be specifically tailored, as the official Google source code only runs on their flagship [[Google Nexus|Nexus]] phone. [[Porting]] Android to specific hardware is a time- and resource-consuming process for device manufacturers, who prioritize their newest devices and often leave older ones behind.<ref name=alliance /> Hence, older smartphones are frequently not updated if the manufacturer decides it is not worth their time, regardless of whether the phone is capable of running the update. This problem is compounded when manufacturers customize Android with their own interface and apps, which must be reapplied to each new release. Additional delays can be introduced by wireless carriers who, after receiving updates from manufacturers, further customize and brand Android to their needs and conduct extensive testing on their networks before sending the update out to users.<ref name=alliance />

The lack of after-sale support from manufacturers and carriers has been widely criticised by consumer groups and the technology media.<ref>{{cite web|author=March 15, 2010 |url=http://consumerist.com/2010/03/15/make-sure-you-know-which-version-of-android-is-on-that-phone-before-buying-it/ |title=Make Sure You Know Which Version Of Android Is On That Phone Before Buying It – The Consumerist |publisher=Consumerist.com |date=2010-03-15 |accessdate=2012-11-24}}</ref><ref name=gu-updates>{{cite web|url=http://www.guardian.co.uk/commentisfree/2012/oct/28/android-smartphone-os-upgrade |title=Android's smartphone OS upgrade issues need more than a quick fix &#124; Dan Gillmor &#124; Comment is free &#124; guardian.co.uk |publisher=Guardian |date=2007-09-28 |accessdate=2012-11-24}}</ref> Some commentators have noted that the industry has a financial incentive ''not'' to update their devices, as the lack of updates for existing devices fuels the purchase of newer ones,<ref>{{cite web|url=http://www.theregister.co.uk/2011/11/22/android_patching_mess/ |title=Security takes a backseat on Android in update shambles |publisher=The Register |date=2011-11-22 |accessdate=2012-11-02}}</ref> an attitude described as "insulting".<ref name=gu-updates /> ''[[The Guardian]]'' has complained that the complicated method of distribution for updates is only complicated because manufacturers and carriers have designed it that way.<ref name=gu-updates /> In 2011, Google partnered with a number of industry players to announce an "Android Update Alliance", pledging to deliver timely updates for every device for 18 months after its release.<ref>{{cite web|url=http://www.slashgear.com/android-update-alliance-examined-results-since-google-io-found-lacking-06177411/ |title=Android Update Alliance examined, results since Google I/O found lacking |publisher=SlashGear |date= |accessdate=2012-09-15}}</ref> As of 2012, this alliance has never been mentioned since.<ref name=alliance />

=== Open source community ===

Android has an active community of developers and enthusiasts who use the Android source code to develop and distribute their own modified versions of the operating system.<ref name=cnetroms>{{cite web|last=McFerran |first=Damien |url=http://reviews.cnet.co.uk/mobile-apps/best-custom-roms-for-the-samsung-galaxy-s2-50007658/ |title=Best custom ROMs for the Samsung Galaxy S2 &#124; Reviews &#124; CNET UK |publisher=Reviews.cnet.co.uk |date=2012-04-17 |accessdate=2012-09-15}}</ref> These community-developed releases often bring new features and updates to devices faster than through the official manufacturer/carrier channels, albeit without as extensive testing or quality assurance;<ref name=apolroms>{{cite web|url=http://www.androidpolice.com/2010/05/01/custom-roms-for-android-explained-and-why-you-want-them/ |title=Custom ROMs For Android Explained - Here Is Why You Want Them |date=2012-08-20 |accessdate=2012-09-15}}</ref> provide continued support for older devices that no longer receive official updates; or bring Android to devices that were officially released running other operating systems, such as the [[HP Touchpad]]. Community releases often come pre-[[Rooting (Android OS)|rooted]] and contain modifications unsuitable for non-technical users, such as the ability to [[overclock]] or [[Dynamic voltage scaling|over/undervolt]] the device's processor.<ref>{{cite web|last=Isaac |first=Mike |url=http://www.wired.com/gadgetlab/2011/04/cyanogenmod-android/ |title=Android OS Hack Gives Virtual Early Upgrade &#124; Gadget Lab |publisher=Wired.com |date=2011-04-11 |accessdate=2012-09-15}}</ref> [[CyanogenMod]] is the most widely used community firmware,<ref>{{cite web|url=http://www.androidpolice.com/2012/05/28/cyanogenmod-has-been-installed-over-2-million-times-doubles-install-numbers-since-january/ |title=CyanogenMod Has Now Been Installed On Over 2 Million Devices, Doubles Install Numbers Since January |publisher=Androidpolice.com |date=2012-05-28 |accessdate=2012-09-15}}</ref> and acts as a foundation for numerous others.

Historically, device manufacturers and mobile carriers have typically been unsupportive of third-party [[firmware]] development. Manufacturers express concern about improper functioning of devices running unofficial software and the support costs resulting from this.<ref name=htcdev>{{cite web| title=Unlock Bootloader | url=http://htcdev.com/bootloader/ | accessdate=2011-10-30}}</ref> Moreover, modified firmwares such as CyanogenMod sometimes offer features, such as [[tethering]], for which carriers would otherwise charge a premium. As a result, technical obstacles including locked [[bootloader]]s and restricted access to root permissions are common in many devices. However, as community-developed software has grown more popular, and following a statement by the Librarian of Congress in the United States that permits the "[[iOS jailbreaking|jailbreaking]]" of mobile devices,<ref>{{cite web|last=Sadun |first=Erica |url=http://www.tuaw.com/2010/07/26/library-of-congress-rules-in-favor-of-jailbreaking/ |title=LoC rules in favor of jailbreaking |publisher=Tuaw.com |date=2010-07-26 |accessdate=2012-09-15}}</ref> manufacturers and carriers have softened their position regarding third party development, with some, including [[HTC]],<ref name=htcdev>{{cite web|url=http://htcdev.com/bootloader |title=HTC's bootloader unlock page |publisher=Htcdev.com |date= |accessdate=2012-09-15}}</ref> [[Motorola]],<ref>{{cite web|author=Monday, October 24th, 2011 |url=http://techcrunch.com/2011/10/24/motorola-offers-unlocked-bootloader-tool-for-droid-razr-verizon-removes-it/ |title=Motorola Offers Unlocked Bootloader Tool |publisher=Techcrunch.com |date=2011-10-24 |accessdate=2012-09-15}}</ref> [[Samsung]]<ref>{{cite web|url=http://www.inspiredgeek.com/2011/06/08/cyanogenmod-7-for-samsung-galaxy-s2-ii-development-already-started/ |title=CyanogenMod 7 for Samsung Galaxy S2 (II): Development Already Started! |date=8 June 2011 |work=Inspired Geek}}</ref><ref>{{cite web|url=http://www.androidcentral.com/cyanogenmod-coming-galaxy-sii-thanks-samsung |title=CyanogenMod coming to the Galaxy S 2, thanks to Samsung |date=6 June 2011 |work=Android Central}}</ref> and [[Sony Mobile Communications|Sony]],<ref>{{cite web|last=Forian |first=Daniel |url=http://developer.sonyericsson.com/wp/2011/09/28/sony-ericsson-supports-independent-developers/ |title=Sony Ericsson supports independent developers – Developer World |publisher=Developer.sonyericsson.com |date= |accessdate=2012-09-15}}</ref> providing support and encouraging development. As a result of this, over time the need to circumvent [[hardware restrictions]] to install unofficial firmware has lessened as an increasing number of devices are shipped with unlocked or unlock''able'' [[bootloader]]s, similar to the [[Google Nexus|Nexus]] series of phones, although usually requiring that users waive their devices' warranties to do so.<ref name=htcdev /> However, despite manufacturer acceptance, some carriers in the US still require that phones are locked down.<ref name=verge-c>{{cite web|last=Kopstein |first=Joshua |url=http://www.theverge.com/2012/11/20/3666668/access-denied-android-unlocked-bootloaders |title=Access Denied: why Android's broken promise of unlocked bootloaders needs to be fixed |publisher=The Verge |date=2012-11-20 |accessdate=2012-11-24}}</ref>

The unlocking and "hackability" of smartphones and tablets remains a source of tension between the community and industry, with the community arguing that unofficial development is increasingly important given the failure of industry to provide timely updates and/or continued support to their devices.<ref name=verge-c />

==Security and privacy==
[[File:PlayStorePermissions.png|thumb|upright|right|App permissions in the Play Store]]
{{See also|Mobile security}}

Android applications run in a [[Sandbox (computer security)|sandbox]], an isolated area of the system that does not have access to the rest of the system's resources, unless access permissions are explicitly granted by the user when the application is installed. Before installing an application, the [[Google Play|Play Store]] displays all required permissions: a game may need to enable vibration or save data to an [[SD card]], for example, but should not need to read [[SMS]] messages or access the phonebook.  After reviewing these permissions, the user can choose to accept or refuse them, installing the application only if they accept.<ref>{{cite web |url=http://source.android.com/tech/security/index.html |title=Android Security Overview |work=Android Open Source Project |accessdate=2012-02-20}}</ref>

The sandboxing and permissions system lessens the impact of vulnerabilities and bugs in applications, but developer confusion and limited documentation has resulted in applications routinely requesting unnecessary permissions, reducing its effectiveness.<ref name="demystified">{{cite paper |first1=Adrienne Porte |last1=Felt |first2=Erika |last2=Chin |first3=Steve |last3=Hanna |first4=Dawn |last4=Song |first5=David |last5=Wagner |url=http://www.cs.berkeley.edu/~afelt/android_permissions.pdf |title=Android Permissions Demystified |accessdate=2012-02-20}}</ref> Several security firms, such as [[Lookout Mobile Security]],<ref>{{cite web |url=http://www.mylookout.com |title=Lookout Mobile Security |publisher=Lookout |accessdate=2012-07-05}}</ref> [[AVG Technologies]],<ref>{{cite web |url=http://www.avg.com/us-en/antivirus-for-android |title=Antivirus for Android Smartphones |publisher=AVG |accessdate=2012-02-16}}</ref> and [[McAfee]],<ref>{{cite web |url=https://www.mcafeemobilesecurity.com/products/android.aspx |title=McAfee Mobile Security for Android |publisher=Mcafeemobilesecurity.com |accessdate=2012-02-16}}</ref> have released antivirus software for Android devices. This software is ineffective as sandboxing also applies to such applications, limiting their ability to scan the deeper system for threats.<ref name = extremetech>http://www.extremetech.com/computing/104827-android-antivirus-apps-are-useless-heres-what-to-do-instead/2 Android antivirus apps are useless, here's what to do instead&nbsp;— access April 10, 2012</ref>

Research from security company [[Trend Micro]] lists premium service abuse as the most common type of Android malware, where text messages are sent from infected phones to [[premium-rate telephone number]]s without the consent or even knowledge of the user.<ref name=micro>{{cite web|last=Protalinski |first=Emil |url=http://www.zdnet.com/android-malware-numbers-explode-to-25000-in-june-2012-7000001046/ |title=Android malware numbers explode to 25,000 in June 2012 |publisher=ZDNet |date=2012-07-17 |accessdate=2012-11-09}}</ref> Other malware displays unwanted and intrusive adverts on the device, or sends personal information to unauthorised third parties.<ref name=micro /> Security threats on Android are reportedly growing exponentially; however, Google engineers have argued that the malware and virus threat on Android is being exaggerated by security companies for commercial reasons,<ref name=exaggeration>{{cite web|url=http://www.pcadvisor.co.uk/news/network-wifi/3320818/mobile-malware-exaggerated-by-charlatan-vendors-says-google-engineer/ |title=Mobile malware exaggerated by "charlatan" vendors, says Google engineer |publisher=PC Advisor |date=2011-11-24 |accessdate=2012-11-09}}</ref><ref name=extremely>{{cite web|url=http://www.androidcentral.com/android-42-brings-new-security-features-scan-sideloaded-apps |title=Android 4.2 brings new security features to scan sideloaded apps |publisher=Android Central |date= |accessdate=2012-11-09}}</ref> and have accused the security industry of playing on fears to sell virus protection software to users.<ref name=exaggeration /> Google maintains that dangerous malware is actually extremely rare.<ref name=extremely />  Indeed, a survey conducted by F-Secure showed that only 0.5% of Android malware reported had come from the Google Play store.<ref>http://www.phonearena.com/news/Android-malware-perspective-only-0.5-comes-from-the-Play-Store_id36696</ref>

Google currently uses their [[Google Bouncer]] malware scanner to watch over and scan the Google Play store apps.<ref>{{cite web|last=Chirgwin|first=Richard|title=Google Bouncer flaw|url=http://www.theregister.co.uk/2012/06/04/breaking_google_bouncer/|work=Tech news site and blog|publisher=The Register|accessdate=20 November 2012}}</ref> It is intended to flag up suspicious apps and warn users of any potential issues with an application before they download it.<ref>{{cite web|last=Whittaker |first=Zack |url=http://www.zdnet.com/google-building-malware-scanner-for-google-play-report-7000005780/ |title=Google building malware scanner for Google Play: report |publisher=ZDNet |date=2012-10-15 |accessdate=2012-11-09}}</ref> Android version 4.2 ''Jelly Bean'' was released in 2012 with enhanced security features, including a malware scanner built into the system, which works in combination with Google Play but can scan apps installed from third party sources as well, and an alert system which notifies the user when an app tries to send a premium-rate text message, blocking the message unless the user explicitly authorises it.<ref>{{cite web|url=http://blogs.computerworld.com/android/21259/android-42-security |title=Exclusive: Inside Android 4.2's powerful new security system &#124; Computerworld Blogs |publisher=Blogs.computerworld.com |date=2012-11-01 |accessdate=2012-11-09}}</ref>

Android smartphones have the ability to report the location of [[Wi-Fi]] access points, encountered as phone users move around, to build databases containing the physical locations of hundreds of millions of such access points. These databases form electronic maps to locate smartphones, allowing them to run apps like [[Foursquare (social network)|Foursquare]], [[Google Latitude]], [[Facebook Places]], and to deliver location-based ads.<ref>{{cite news |url=http://www.nytimes.com/2011/05/09/technology/09google.html?scp=1&sq=Skyhook%20Wireless%20v.%20Google%20Case%20Yields%20E-Mail%20Insight&st=cse |title=Suit Opens a Window Into Google |author=Steve Lohr |work=[[The New York Times]] |date=May 8, 2011   |issn=0362-4331 |accessdate=2012-02-16}}</ref> Third party monitoring software such as TaintDroid,<ref>{{cite web |url=http://appanalysis.org/faq.html |title=AppAnalysis.org: Real Time Privacy Monitoring on Smartphones |accessdate=2012-02-21}}</ref> an academic research-funded project, can, in some cases, detect when personal information is being sent from applications to remote servers.<ref>{{cite web|last=Ganapati |first=Priya |url=http://www.wired.com/gadgetlab/2010/09/data-collection-android/ |title=Study Shows Some Android Apps Leak User Data Without Clear Notifications &#124; Gadget Lab |publisher=Wired.com |date=September 30, 2010 |accessdate=2012-01-30}}</ref>

== Licensing ==

The [[source code]] for Android is available under [[free and open source software]] licenses. [[Google]] publishes most of the code (including network and telephony [[solution stack|stacks]])<ref>{{cite news |url=http://www.eweek.com/c/a/Mobile-and-Wireless/Google-Open-Sources-Android-on-Eve-of-G1-Launch/ |work=[[eWeek]] |title=Google Open-Sources Android on Eve of G1 Launch |first=Clint |last=Boulton |date=October 21, 2008 |accessdate=2012-02-17}}</ref> under the [[Apache License]] version 2.0,<ref>{{cite web |url=http://source.android.com/posts/opensource |title=Android is now available as open source |work = Android Open Source Project |first=Dave |last=Bort |date=October 21, 2008 |archiveurl=http://web.archive.org/web/20090228170042/http://source.android.com/posts/opensource |archivedate=February 28, 2009 |accessdate=2012-02-16}}</ref><ref>{{cite web |url=http://arstechnica.com/old/content/2007/11/why-google-chose-the-apache-software-license-over-gplv2.ars |title=Why Google chose the Apache Software License over GPLv2 for Android |author=Ryan Paul |work=Ars Technica |date=November 6, 2007 |accessdate=2012-02-16}}</ref> and the rest, Linux kernel changes, under the [[GNU General Public License]] version 2. The [[Open Handset Alliance]] develops the changes to the Linux kernel, in public, with source code publicly available at all times. The rest of Android is developed in private by Google, with source code released publicly when a new version is released. Typically Google collaborates with a hardware manufacturer to produce a 'flagship' device (part of the [[Google Nexus]] series) featuring the new version of Android, then makes the source code available after that device has been released.<ref>{{cite web |url=http://source.android.com/faqs.html#what-is-involved-in-releasing-the-source-code-for-a-new-android-version |title=Frequently Asked Questions: What is involved in releasing the source code for a new Android version? |work=Android Open Source Project |accessdate=2012-02-16}}</ref>

In early 2011, Google chose to temporarily withhold the Android source code to the tablet-only 3.0 ''Honeycomb'' release. The reason, according to [[Andy Rubin]] in an official Android blog post, was because ''Honeycomb'' was rushed for production of the [[Motorola Xoom]],<ref>{{cite web |last=Bray |first=Tim |url=http://android-developers.blogspot.com/2011/04/i-think-im-having-gene-amdahl-moment.html |title=Android Developers Blog: I think I'm having a Gene Amdahl moment |publisher=Android-developers.blogspot.com |date=April 6, 2011 |accessdate=2012-02-16}}</ref> and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets.<ref>{{cite web |author=Jerry Hildenbrand |url=http://www.androidcentral.com/google-not-open-sourcing-honeycomb-says-bloomberg |title=Honeycomb won't be open-sourced? Say it ain't so! |publisher=Androidcentral.com |date=March 24, 2011 |accessdate=2012-02-16}}</ref> The source code was once again made available in November 2011 with the release of Android 4.0.<ref name="40sourcerel">{{cite web |url=http://www.osnews.com/story/25330/Android_4_0_Ice_Cream_Sandwich_Source_Code_Released |title=Android 4.0 Ice Cream Sandwich Source Code Released |author=Thom Holwerda |work=OSNews |date=November 14, 2011 |accessdate=2012-02-16}}</ref>

Even though the software is open-source, device manufacturers cannot use Google's Android trademark unless Google certifies that the device complies with their Compatibility Definition Document (CDD). Devices must also meet this definition to be eligible to license Google's closed-source applications, including [[Google Play]].<ref name="Compatibility_FAQ">{{cite web |url= http://source.android.com/faqs.html#compatibility |title=Android Open Source Project Frequently Asked Questions: Compatibility|work=source.android.com |accessdate=13 March 2011}}</ref> As Android is not completely released under a GPL compatible license, e.g. Google's code is under the [[Apache license]],<ref name="Licenses">{{cite web|url=http://source.android.com/source/licenses.html|title=Licenses|work=Android Open Source Project.|publisher=Open Handset Alliance|accessdate=2012-09-09|date=|quote=''The preferred license for the Android Open Source Project is the Apache Software License, 2.0. [...] Why Apache Software License? [...] For userspace (that is, non-kernel) software, we do in fact prefer ASL2.0 (and similar licenses like BSD, MIT, etc.) over other licenses such as LGPL. Android is about freedom and choice. The purpose of Android is promote openness in the mobile world, but we don't believe it's possible to predict or dictate all the uses to which people will want to put our software. So, while we encourage everyone to make devices that are open and modifiable, we don't believe it is our place to force them to do so. Using LGPL libraries would often force them to do so.''|language=englisch}}</ref> and also because Google Play allows proprietary software, [[Richard Stallman]] and the [[Free Software Foundation]] have been critical of Android and have recommended the usage of alternatives such as [[Replicant (operating system)|Replicant]].<ref name="stallman2011">{{cite web|url=http://www.guardian.co.uk/technology/2011/sep/19/android-free-software-stallman|publisher=The Guardian |title=Is Android really free software? - Google's smartphone code is often described as 'open' or 'free' – but when examined by the Free Software Foundation, it starts to look like something different|first=Richard |last=Stallman |date=2011-09-19|accessdate=2012-09-09|quote=''the software of Android versions 1 and 2 was mostly developed by Google; Google released it under the Apache 2.0 license, which is a lax free software license without copyleft. [...] The version of Linux included in Android is not entirely free software, since it contains non-free "binary blobs" [...] Android is very different from the GNU/Linux operating system because it contains very little of GNU.''}}</ref><ref>{{cite web|url=http://www.gnu.org/philosophy/android-and-users-freedom.html|title=Android and Users' Freedom - Support the Free Your Android campaign|first=Richard|last=Stallman |publisher=gnu.org |quote=''Even though the Android phones of today are considerably less bad than Apple or Windows smartphones, they cannot be said to respect your freedom.'' |date=2012-08-05 |accessdate=2012-09-09}}</ref>

== Reception ==

Android received a lukewarm reaction when it was unveiled in 2007. Although analysts were impressed with the respected technology companies that had partnered with Google to form the Open Handset Alliance, it was unclear whether mobile phone manufacturers would be willing to replace their existing operating systems with Android.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/7080758.stm |title=Technology &#124; Q&A: Google's Android |publisher=BBC News |date=2007-11-06 |accessdate=2012-11-09}}</ref> The idea of an open source, Linux-based [[Computing platform|development platform]] sparked interest,<ref>{{cite web|last=Reardon |first=Marguerite |url=http://news.cnet.com/8301-17938_105-9869123-1.html |title=Google Android prototypes debut at MWC &#124; Crave - CNET |publisher=News.cnet.com |date=2008-02-11 |accessdate=2012-11-09}}</ref> but there were additional worries about Android facing strong competition from established players in the smartphone market, such as Nokia and Microsoft, and rival Linux mobile operating systems that were in development.<ref>{{cite web|url=http://www.smh.com.au/news/biztech/androids-outing-at-barcelona/2008/02/12/1202760277773.html?page=2 |title=Android's outing at Barcelona - BizTech - Technology |publisher=smh.com.au |date=2008-02-12 |accessdate=2012-11-09}}</ref> These established players were skeptical: [[Nokia]] was quoted as saying "we don't see this as a threat,"<ref name=lol /> and a member of [[Microsoft]]'s [[Windows Mobile]] team stated "I don't understand the impact that they are going to have."<ref name=lol>{{cite web|url=http://www.engadget.com/2007/11/05/symbian-nokia-microsoft-and-apple-downplay-android-relevance/ |title=Symbian, Nokia, Microsoft and Apple downplay Android relevance |publisher=Engadget |date= |accessdate=2012-11-09}}</ref>

Since then Android has grown to become the most widely used smartphone operating system<ref name=ars5th>{{cite web|last=Brodkin |first=Jon |url=http://arstechnica.com/gadgets/2012/11/on-androids-5th-birthday-5-things-we-love-about-android/ |title=On its 5th birthday, 5 things we love about Android |publisher=Ars Technica |date=2012-11-05 |accessdate=2012-11-09}}</ref> and "one of the fastest mobile experiences available."<ref name=syrup>{{cite web|url=http://mobilesyrup.com/2012/11/05/on-its-fifth-birthday-android-is-closer-to-our-actual-vision-for-mobile-supremacy/ |title=On its fifth birthday, Android is "closer to our actual vision" for mobile supremacy |publisher=MobileSyrup.com |date= |accessdate=2012-11-09}}</ref> Reviewers have highlighted the open source nature of the operating system as one of its defining strengths, allowing companies such as Amazon ([[Kindle Fire]]), [[Barnes & Noble]] ([[Barnes & Noble Nook|Nook]]), [[Ouya]], [[Baidu]], and others to [[Fork (software development)|fork]] the software and release hardware running their own customised version of Android. As a result, it has been described by technology website [[Ars Technica]] as "practically the default operating system for launching new hardware" for companies without their own mobile platforms.<ref name=ars5th /> This openness and flexibility is also present at the level of the end user: Android allows extensive customisation of devices by their owners and apps are freely available from non-Google app stores and third party websites. These have been cited as among the main advantages of Android phones over others.<ref name=ars5th /><ref>{{cite web|url=http://www.androidauthority.com/best-apps-customizing-personalizing-android-phones-100685/ |title=Best Android apps for personalizing and customizing your phone |publisher=Androidauthority.com |date=2012-07-13 |accessdate=2012-11-09}}</ref>

Despite its success on smartphones, Android tablet adoption has been slow.<ref>{{cite web|author=Wilson Rothman |url=http://www.nbcnews.com/technology/technolog/why-ipad-stomping-android-tabs-24-1-121875 |title=Why iPad is stomping Android tabs 24 to 1 - Technology on |publisher=Nbcnews.com |date=2012-10-24 |accessdate=2012-11-09}}</ref> This is primarily blamed on a [[chicken or the egg]] situation where consumers are hesitant to buy an Android tablet due to a lack of high quality tablet apps, but developers are hesitant to spend time and resources developing tablet apps until there's a significant market for them.<ref>{{cite web|author= Kevin C. Tofel|url=http://gigaom.com/mobile/what-devs-say-about-ipad-but-not-android-tablets/ |title=What devs say about iPad (but not Android tablets) |publisher=Gigaom.com |date=2012-03-19 |accessdate=2012-11-09}}</ref><ref name=tabs>{{cite web|url=http://www.zdnet.com/blog/mobile-news/why-there-arent-more-android-tablet-apps-by-the-numbers/7218 |title=Why there aren't more Android tablet apps, by the numbers |publisher=ZDNet |date=2012-03-21 |accessdate=2012-11-09}}</ref> Other factors included high prices<ref>{{cite web|last=Hiner |first=Jason |url=http://www.techrepublic.com/blog/hiner/why-android-tablets-failed-a-postmortem/10011 |title=Why Android tablets failed: A postmortem |publisher=TechRepublic |date=2012-01-05 |accessdate=2012-11-09}}</ref> and the dominance of Apple's [[iPad]].<ref name=tabs /> This began to change in 2012 with the release of the successful [[Nexus 7]] and a push by Google for developers to write better tablet apps.<ref>{{cite web|last=Cunningham |first=Andrew |url=http://arstechnica.com/gadgets/2012/10/google-to-android-devs-make-nicer-tablet-apps-pretty-please/ |title=Google to Android devs: make nicer tablet apps, pretty please? |publisher=Ars Technica |date=2012-10-08 |accessdate=2012-11-09}}</ref> Android tablets are expected to overtake the iPad within a few years.<ref>{{cite web|author= |url=http://techcrunch.com/2012/11/28/ipad-and-android-tablet-market-share-margin-narrows-much-faster-than-originally-predicted/ |title=iPad And Android Tablet Market Share Margin Narrows Much Faster Than Originally Predicted |publisher=TechCrunch |date=2012-11-28 |accessdate=2012-12-01}}</ref>

=== Market share and rate of adoption ===

Research company Canalys estimated in the second quarter of 2009 that Android had a 2.8% share of worldwide [[smartphone]] shipments.<ref name="Insider_1">{{cite news |title=Canalys: iPhone outsold all Windows Mobile phones in Q2 2009 |url=http://www.appleinsider.com/articles/09/08/21/canalys_iphone_outsold_all_windows_mobile_phones_in_q2_2009.html |author=Prince McLean |newspaper=[[AppleInsider]] |date=August 21, 2009 |accessdate=2012-02-16}}</ref> By the fourth quarter of 2010 this had grown to 33% of the market, becoming the top-selling smartphone platform.<ref name="canalysQ42010"/> By the third quarter of 2011 [[Gartner]] estimated that more than half (52.5%) of the smartphone market belongs to Android.<ref>{{cite web |url=http://www.gartner.com/it/page.jsp?id=1848514 |title=Gartner Says Sales of Mobile Devices Grew 5.6 Percent in Third Quarter of 2011; Smartphone Sales Increased 42 Percent |date=November 15, 2011 |accessdate=2012-02-16}}</ref> By the third quarter of 2012 Android had a 75% share of the global smartphone market according to the research firm IDC.<ref name=idcQ3 />

In July 2011, Google said that 550,000 new Android devices were being activated every day,<ref name=a550>{{cite web |url=http://techcrunch.com/2011/07/14/android-now-seeing-550000-activations-per-day/ |title=Android Now Seeing 550,000 Activations Per Day |first=Greg |last=Kumparak |work=Techcrunch |date=July 14, 2011 |accessdate=2012-02-16}}</ref> up from 400,000 per day in May,<ref>{{cite news |url=http://news.yahoo.com/google-activates-500-000-android-devices-day-may-145858294.html |title=Google activates 500,000 Android devices a day, may reach 1 million in October |work=Yahoo News |author=Jeffrey Van Camp |date=Jun 28, 2011 |accessdate=2012-02-16}}</ref> and more than 100 million devices had been activated<ref name="i/o 2011 stats">{{cite web |url=http://googleblog.blogspot.com/2011/05/android-momentum-mobile-and-more-at.html |title=Android: momentum, mobile and more at Google I/O |first=Hugo |last=Barra |work=The Official Google Blog |date=May 10, 2011 |accessdate=2012-02-16}}</ref> with 4.4% growth per week.<ref name=a550 /> In September 2012, 500 million devices had been activated with 1.3 million activations per day.<ref name="Google Team" /><ref name="Eric Schmidt" />

Android market share varies by location. In July 2012, Android's market share in the United States was 52%,<ref>{{cite web|last=Fingas |first=Jon |url=http://www.engadget.com/2012/09/04/comscore-android-tops-52-percent-of-us-smartphone-share/ |title=ComScore: Android tops 52 percent of US smartphone share, iPhone cracks the 33 percent mark |publisher=Engadget.com |date=2012-09-04 |accessdate=2012-11-24}}</ref> but this rises to 90% in China.<ref>{{cite web|url=http://www.techinasia.com/android-market-share-china-2012/ |title=Report: Android Rises to 90% of Smartphone Market in China |publisher=Techinasia.com |date= |accessdate=2012-11-24}}</ref>

=== Usage share of Android versions ===
[[File:Android chart.png|thumb|250px|Usage share of the different versions as of December 3, 2012]]

Usage share of the different versions as of February 5, 2013.<ref>{{cite web |url=http://developer.android.com/about/dashboards/index.html |title=Android Platform Versions |work=Android Developers |quote=Based on the number of Android devices that have accessed the Play Store within a 14-day period ending on the data collection date noted below. |date=January 3, 2013 |accessdate= January 21, 2013}}</ref> Most Android devices to date still run the older OS version 2.3 ''Gingerbread'' that was released on December 6, 2010, due to most lower-end devices still being released with it.

{| class="wikitable sortable" style="text-align:right"
;
! Version
! Code name
! Release date
! [[application programming interface|API]] level
! Distribution (February 5, 2013)
|-
| style="text-align:center;" | '''[[Jelly Bean (operating system)|4.2]]'''
| [[Jelly Bean (operating system)|''Jelly Bean'']]
| November 13, 2012
| 17
| 1.4%
|-
| style="text-align:center;" | '''[[Jelly Bean (operating system)|4.1.x]]'''
| [[Jelly Bean (operating system)|''Jelly Bean'']]
| July 9, 2012
| 16
| 12.2%
|-
| style="text-align:center;" | '''[[Ice Cream Sandwich (operating system)|4.0.x]]'''
| [[Ice Cream Sandwich (operating system)|''Ice Cream Sandwich'']]
| December 16, 2011
| 15
| 29.0%
|-
| style="text-align:center;" | '''[[Honeycomb (operating system)|3.2]]'''

| [[Honeycomb (operating system)|''Honeycomb'']]
| July 15, 2011
| 13
| 1.0%
|-
| style="text-align:center;" | '''[[Honeycomb (operating system)|3.1]]'''
| [[Honeycomb (operating system)|''Honeycomb'']]
| May 10, 2011
| 12
| 0.3%
|-
| style="text-align:center;" | '''[[Android 2.3|2.3.3–2.3.7]]'''
| [[Android 2.3|''Gingerbread'']]
| February 9, 2011
| 10
| 45.4%
|-
| style="text-align:center;" | '''[[Android 2.3|2.3–2.3.2]]'''
| [[Android 2.3|''Gingerbread'']]
| December 6, 2010
| 9
| 0.2%
|-
| style="text-align:center;" | '''[[Android Froyo|2.2]]'''

| [[Android Froyo|''Froyo'']]
| May 20, 2010
| 8
| 8.1%
|-
| style="text-align:center;" | '''[[Android version history#Android 2.0, 2.1 Eclair|2.0–2.1]]'''
| [[Android version history#Android_2.0.2F2.1_Eclair|''Eclair'']]

| October 26, 2009
| 7
| 2.2%
|-
| style="text-align:center;" | '''[[Donut (operating system)|1.6]]'''

| [[Donut (operating system)|''Donut'']]
| September 15, 2009
| 4
| 0.2%
|}

=== Application piracy ===
There has been some concern about the ease with which paid Android apps can be [[Copyright infringement of software|pirated]].<ref name=piracy>{{cite web|author=By Wired UK |url=http://www.wired.com/gamelife/2012/05/wired-uk-android-game-piracy/ |title=Op-Ed: Android Piracy Is Huge Problem for Game Devs &#124; Game&#124;Life |publisher=Wired.com |date=2012-05-03 |accessdate=2012-09-15}}</ref> In a May 2012 interview with [[Eurogamer]], the developers of [[Football Manager]] stated that the ratio of pirated players vs legitimate players was 9:1 for their game Football Manager Handheld.<ref>{{cite web|last=Yin |first=Wesley |url=http://www.eurogamer.net/articles/2012-04-24-football-manager-dev-hopes-to-stick-with-android-despite-9-1-piracy-rate |title=Football Manager dev hopes to stick with Android despite 9:1 piracy rate|publisher=Eurogamer.net |date=2012-04-24 |accessdate=2012-09-15}}</ref> However, not every developer agreed that piracy rates were an issue; for example, in July 2012 the developers of the game Wind-up Knight said that piracy levels of their game were only 12%, and most of the piracy came from China, where people cannot purchase apps from Google Play.<ref>{{cite web|last=Armasu |first=Lucian |url=http://www.androidauthority.com/piracy-rates-are-higher-ios-android-wind-up-knight-developer-104305/ |title=Wind-up Kinght developer: Piracy rates on iOS and Android are comparable, China is the main source|publisher=Androidauthority.com |date=July 30, 2012 |accessdate=2012-10-06}}</ref> 

In 2010, Google released a tool for validating authorised purchases for use within apps, but developers complained that this was insufficient and trivial to [[Software cracking|crack]]. Google responded that the tool, especially its initial release, was intended as a sample framework for developers to modify and build upon depending on their needs, not as a finished security solution.<ref>{{cite web|last=Paul |first=Ryan |url=http://arstechnica.com/gadgets/2010/08/google-cracked-android-anti-piracy-system-used-wrong-by-devs/ |title=Android antipiracy cracked, Google says devs used it wrong |publisher=Ars Technica |date=2010-08-25 |accessdate=2012-09-15}}</ref> In 2012 Google released a feature in Android 4.1 that encrypted paid applications so that they would only work on the device on which they were purchased, but this feature has been temporarily deactivated due to technical issues.<ref>{{cite web|last=McAllister|first=Neil|url=http://www.theregister.co.uk/2012/08/08/android_drm_disabled/ |title=Android app DRM quietly disabled due to bug |publisher=The Register |date=August 8, 2012 |accessdate=2012-06-10}}</ref>

== Copyrights and patents ==
{{further|Oracle v. Google|Smartphone wars|Patent troll}}

Both Android and Android phone manufacturers have been involved in numerous patent lawsuits. On August 12, 2010, [[Oracle Corporation|Oracle]] sued Google over claimed infringement of copyrights and patents related to the [[Java (programming language)|Java]] programming language.<ref name="computerworld">{{cite web |url=http://www.computerworld.com/s/article/9180678/Update_Oracle_sues_Google_over_Java_use_in_Android |title=Update: Oracle sues Google over Java use in Android |first=James |last=Niccolai |date=August 12, 2010 |work=Computerworld |publisher=International Data Group Inc |accessdate=2012-02-16}}</ref> Oracle originally sought damages up to $6.1 billion,<ref>{{cite news|url=http://www.reuters.com/article/2011/06/18/us-oracle-google-lawsuit-idUSTRE75H0FP20110618|title=Oracle seeks up to $6.1 billion in Google lawsuit|publisher=Reuters|date=June 18, 2011|accessdate=September 7, 2011}}</ref> but this valuation was rejected by a United States federal judge who asked Oracle to revise the estimate.<ref>{{cite web|url=http://www.mercurynews.com/news/ci_18532705|title=Judge tosses Oracle's $6.1 billion damage estimate in claim against Google|publisher=MercuryNews.com|date=July 22, 2011|accessdate=September 7, 2011}}</ref>  In response, Google submitted multiple lines of defense, counterclaiming that Android did not infringe on Oracle's patents or copyright, that Oracle's patents were invalid, and several other defenses. They said that Android is based on [[Apache Harmony]], a [[clean room design|clean room]] implementation of the Java class libraries, and an independently developed virtual machine called [[Dalvik (software)|Dalvik]].<ref>{{cite web |url=http://www.wired.com/epicenter/2010/10/google-oracle-android/ |title=Calling Oracle Hypocritical, Google Denies Patent Infringement |first=Ryan |last=Singel |date=October 5, 2010 |work=Wired |accessdate=2012-02-16}}</ref> In May 2012 the jury in this case found that Google did not infringe on Oracle's patents, and the trial judge ruled that the structure of the Java APIs used by Google was not copyrightable.<ref>{{cite web | url=http://www.zdnet.com/blog/btl/jury-clears-google-of-infringing-on-oracle-patents/77897 | title=Jury clears Google of infringing on Oracle's patents | author = Josh Lowensohn | work=ZDNet | date = May 23, 2012 | accessdate=2012-05-25}}</ref><ref>
{{cite web | title = Google wins crucial API ruling, Oracle's case decimated | url = http://arstechnica.com/tech-policy/2012/05/google-wins-crucial-api-ruling-oracles-case-decimated/ | author = Joe Mullin | work =  Ars Technica | date = May 31, 2012 | accessdate = 2012-06-01 }}
</ref>

In addition to lawsuits against Google directly, various [[proxy war]]s have been waged against Android indirectly by targeting manufacturers of Android devices, with the effect of discouraging manufacturers from adopting the platform by increasing the costs of bringing an Android device to market.<ref name=pcworld>{{cite web|last=Newman |first=Jared |url=http://www.pcworld.com/article/240783/microsoftsamsung_patent_deal_great_news_for_windows_phones.html |title=Microsoft-Samsung Patent Deal: Great News for Windows Phones |publisher=PCWorld |date=2011-09-28 |accessdate=2012-09-15}}</ref> Both [[Apple Inc.|Apple]] and [[Microsoft]] have sued several manufacturers for patent infringement, with Apple's ongoing [[Apple Inc. v. Samsung Electronics Co., Ltd.|legal action against Samsung]] being a particularly high-profile case. In October 2011 Microsoft said they had signed patent license agreements with ten Android device manufacturers, whose products account for 55% of the  worldwide revenue for Android devices.<ref name="10agreements">{{cite web |title=Microsoft collects license fees on 50% of Android devices, tells Google to "wake up" |url=http://arstechnica.com/microsoft/news/2011/10/microsoft-collects-license-fees-on-50-of-android-devices-tells-google-to-wake-up.ars |work=[[Ars Technica]] |accessdate=2012-02-16}}</ref> These include [[Samsung]] and [[HTC]].<ref>{{cite web |url=http://www.computerworld.com/s/article/9220357/Microsoft_signs_Android_licensing_deal_with_Samsung |title=Microsoft signs Android licensing deal with Samsung |author=Mikael Ricknäs |work=Computerworld |date=September 28, 2011 |accessdate=2012-02-16}}</ref> Samsung's patent settlement with Microsoft includes an agreement that Samsung will allocate more resources to developing and marketing phones running Microsoft's [[Windows Phone]] operating system.<ref name=pcworld />

Google has publicly expressed its frustration for the current patent landscape in the United States, accusing Apple, Oracle and Microsoft of trying to take down Android through patent litigation, rather than innovating and competing with better products and services.<ref name="bully">{{cite web |title=Google publicly accuses Apple, Microsoft, Oracle of patent bullying |url=http://arstechnica.com/tech-policy/news/2011/08/google-publicly-accuses-apple-microsoft-oracle-of-patent-bullying.ars |author=Jacqui Cheng |date=August 3, 2011 |accessdate=2012-02-16}}</ref> In 2011-2, Google purchased [[Motorola Mobility]] for [[USD|US$]]12.5 billion, which was viewed in part as a defensive measure to protect Android, since Motorola Mobility held more than 17,000 patents.<ref name="moto">{{cite web |title=Google, needing patents, buys Motorola wireless for $12.5 billion |url=http://arstechnica.com/gadgets/news/2011/08/google-to-buy-motorola-in-effort-to-defend-itself-from-patent-bullies.ars |author=Casey Johnston |date=August 15, 2011 |accessdate=2012-02-16}}</ref> In December 2011 Google bought over a thousand patents from [[IBM]].<ref name="arsibm">{{cite web |url=http://arstechnica.com/gadgets/news/2012/01/google-buys-another-round-of-ibm-patents-as-oracle-trial-nears.ars |title=Google buys another round of IBM patents as its Oracle trial nears
|publisher=[http://arstechnica.com/ Ars Technica] |last=Paul |first=Ryan |date=January 4, 2012 |accessdate=2012-02-16}}</ref>

== Beyond smartphones and tablets ==
[[File:SmartWatch MN2 auf der Internationalen Funkausstellung 2012 in Berlin 1 PD.JPG|thumb|150px|right|The [[Sony SmartWatch]]: an example of how Android is used on electronics other than smartphones and tablets]]
The open and customizable nature of Android allows it to be used on other electronics, including [[laptop]]s and [[netbook]]s, [[smartbook]]s<ref>{{cite web |url=http://www.engadget.com/2010/09/06/toshiba-ac100-android-smartbook-hits-the-united-kingdom/ |title=Toshiba AC100 Android smartbook hits the United Kingdom |author=Laura June |work=Engadget |date=September 6, 2010 |accessdate=2012-02-20}}</ref> [[smart TV]]s ([[Google TV]]) and cameras ([[Nikon Coolpix S800c]] and [[Galaxy Camera]]).<ref>{{cite web|url=http://www.engadget.com/2010/10/03/altek-leo-the-14-megapixel-android-cameraphone-headed-for-euro/ |title=Altek Leo, the 14 megapixel Android cameraphone, headed for Europe in 2011 |publisher=Engadget |date=October 3, 2010 |accessdate=2012-01-04}}</ref><ref>{{cite web|url=http://www.samsung.com/in/promotions/galaxycamera/?pid=in_home_thelatest_left1_galaxycamera_20120830|title=Samsung Galaxy Camera |author=Samsung |work=Samsung.com |date=August 29, 2012 |accessdate=2012-08-30}}</ref> In addition, the Android operating system has seen applications on smart glasses ([[Project Glass]]), [[wristwatch]]es,<ref>{{cite web |last=Hollister |first=Sean |url=http://www.theverge.com/2012/1/10/2695959/sony-smart-watch-aka-sony-ericsson-liveview-2-hands-on |title=Sony Smart Watch (aka Sony Ericsson LiveView 2) hands-on |publisher=The Verge |date=January 10, 2012 |accessdate=2012-02-16}}</ref> [[headphones]],<ref>{{cite web |url=http://www.theregister.co.uk/2011/01/12/now_audio_admiral_touch/ |title=Android-powered touchscreen Wi-Fi headphones |author=Rik Myslewski |publisher=theregister.co.uk |date=January 12, 2011 |accessdate=2012-01-16}}</ref> car CD and DVD players,<ref>{{cite web |url=http://www.alibaba.com/showroom/car-player-android.html |title=Car Player Android-Car Player Android Manufacturers, Suppliers and Exporters on |publisher=Alibaba.com |accessdate=2012-02-20}}</ref> mirrors,<ref>{{cite web|url=http://www.androidauthority.com/android-everywhere-10-types-of-devices-that-android-is-making-better-57012/ |title=Android Everywhere: 10 Types of Devices That Android Is Making Better |publisher=Androidauthority.com |date=2012-02-26 |accessdate=2012-09-15}}</ref> [[portable media player]]s<ref>{{cite web |url=http://www.androidauthority.com/top-android-mp3-players-for-2011-36523/ |title=Top Android MP3 Players for 2011 |author=Will G. |publisher=Androidauthority.com |date=December 1, 2011 |accessdate=2012-02-16}}</ref> and [[landlines]].<ref>{{cite web|url=http://www.androidcentral.com/archos-smart-home-phone-now-available-get-android-your-landline |title=Archos Smart Home Phone now available - get Android on your landline |publisher=Android Central |date=January 19, 2012 |accessdate=2012-01-30}}</ref> [[Ouya]], an upcoming videogames console running Android, became one of the most successful [[Kickstarter]] campaigns, [[crowdfunding]] US$8.5m for its development,<ref name=ouya>{{cite web|url=http://www.destructoid.com/ouya-interview-julie-uhrman-tackles-consoles-critics-231474.phtml |title=OUYA interview: Julie Uhrman tackles consoles & critics |publisher=Destructoid |date= |accessdate=2012-11-02}}</ref><ref>{{cite web|author=Erik Kain |url=http://www.forbes.com/sites/erikkain/2012/07/16/an-interview-with-ouya-founder-julie-uhrman-on-a-new-breed-of-video-game-console/ |title=An Interview With 'Ouya' Founder Julie Uhrman On A New Breed Of Video Game Console |publisher=Forbes |date=2012-04-18 |accessdate=2012-11-02}}</ref> and was later followed by other Android-based video games consoles such as [[Project Shield]] from [[NVIDIA]].

In 2011, Google demonstrated  "Android@Home", a new home automaton technology which uses Android to control a range of household devices including light switches, power sockets and thermostats.<ref>{{cite web|url=http://www.engadget.com/2011/05/11/editorial-android-home-is-the-best-worst-thing-that-could-happe/ |title=Editorial: Android@Home is the best worst thing that could happen to home automation |publisher=Engadget |date= |accessdate=2012-11-02}}</ref> Prototype light bulbs were announced that could be controlled from an Android phone or tablet, but Android head Andy Rubin was cautious to note that "turning a lightbulb on and off is nothing new," pointing to numerous failed home automation services. Google, he said, was thinking more ambitiously and the intention was to use their position as a [[cloud computing|cloud]] services provider to bring Google products into customers' homes.<ref>{{cite web|author=Nilay Patel |url=http://www.theverge.com/2012/2/27/2827615/android-home-automation-cloud-services-andy-rubin |title=Home in the clouds: Google's home automation platform to have major services integration |publisher=The Verge |date=2012-02-27 |accessdate=2012-11-02}}</ref>

== See also ==
{{Portal|Google|Free software}}
* [[Android version history]]
* [[List of GPS software for mobile phones]]
* [[Comparison of mobile operating systems]]
* [[Rooting (Android OS)]]

* [[Index of Android OS articles]]

== References ==
{{Reflist|30em}}

== External links ==
{{Commons category}}
* {{Official website|http://www.android.com/}}
* {{youtube|1FJHYqE0RDg|Sergey Brin introduces the Android platform}}
<!--* [http://www.stanford.edu/class/ee380/Abstracts/071128.html Android: Building a Mobile Platform to Change the Industry]: lecture given by Google Mobile Platforms Manager, Richard Miner at [[Stanford University]] ([http://ee380.stanford.edu/cgi-bin/videologger.php?target=071128-ee380-300.asx video archive])
* [http://technologeeks.com/Courses/Android-Excerpt.pdf Android Internals: Fragment of a course detailing the architecture of Android and interaction of its components]-->

{{Android}}
{{Mobile operating systems}}
{{Mobile phones}}
{{Linux}}
{{Google Inc.}}

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[[Category:Article Feedback 5 Additional Articles]]
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