Android is a Linux-based operating system for mobile devices such as smartphones and tablet computers, developed by Google in conjunction with the Open Handset Alliance.^[2] The first Android-powered phone was sold in October 2008,^[8] and by the end of 2010 Android had become the world's leading smartphone platform.^[9] It had a worldwide smartphone market share of 59% at the beginning of 2012,^[10] and as of third quarter 2012, there were 500 million devices activated and 1.3 million activations per day.^[11][12]

Android was initially developed by Android Inc, whom Google financially backed and later purchased in 2005.^[13] The unveiling of the Android distribution in 2007 was announced with the founding of the Open Handset Alliance, a consortium of 86 hardware, software, andtelecommunication companies devoted to advancing open standards for mobile devices.^[14]

Google releases the Android code as open-source, under the Apache License.^[15] TheAndroid Open Source Project (AOSP) is tasked with the maintenance and further development of Android.^[16] Additionally, Android has a large community of developers writing applications ("apps") that extend the functionality of devices. Developers write primarily in a customized version of Java,^[17] and apps can be downloaded from online stores such asGoogle Play (formerly Android Market), the app store run by Google, or third-party sites. In June 2012, there were more than 600,000 apps available for Android, and the estimated number of applications downloaded from Google Play was 20 billion.^[18]