Android is a mobile operating system initially developed by Android Inc., a firm purchased by Google in 2005. Android is based upon a modified version of the Linux kernel. It is a participant in the Open Handset Alliance. Unit sales for Android OS smartphones ranked first among all smartphone OS handsets sold in the U.S. in the second and third quarter of 2010, with a third quarter market share of 43.6%.
Android has a large community of developers writing application programs ("apps") that extend the functionality of the devices. There are currently over 100,000 apps available for Android. Android Market is the online app store run by Google, though apps can be downloaded from third party sites (except on AT&T, which disallows this). Developers write in the Java language, controlling the device via Google-developed Java libraries.
The unveiling of the Android distribution on 5 November 2007 was announced with the founding of the Open Handset Alliance, a consortium of 78 hardware, software, and telecom companies devoted to advancing open standards for mobile devices. Google released most of the Android code under the Apache License, a free software and open source license.
The Android operating system software stack consists of Java applications running on a Java based object oriented application frameworkon top of Java core libraries running on a Dalvik virtual machine featuring JIT compilation. Libraries written in C include the surface manager, OpenCore media framework, SQLite relational database management system, OpenGL ES 2.0 3D graphics API, WebKit layout engine, SGL graphics engine, SSL, and Bionic libc. The Android operating system consists of 12 million lines of code including 3 million lines of XML, 2.8 million lines of C, 2.1 million lines of Java, and 1.75 million lines of C++.
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