Android Operating System

A Linux-based operating system designed primarily for touchscreen mobile devices such as smart phones and tablet computers. Initially developed by Android, Inc., which Google backed financially and later purchased in 2005, Android was unveiled in 2007 along with the founding of the Open Handset Alliance: a consortium of hardware, software, and telecommunication companies devoted to advancing open standards for mobile devices. The first Android-powered phone was sold in October 2008.

Android is open source and Google releases the code under the Apache License. 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 ("apps") that extend the functionality of devices, written primarily in a customized version of the Java programming language. 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.

These factors have allowed Android to become the world's most widely used smart phone platform and the software of choice for technology companies who require

• Low-cost
• Customizable
• Lightweight operating system for high tech devices without developing one from scratch

As a result, despite being primarily designed for phones and tablets, it has seen additional applications on televisions, games consoles 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 or bring Android to devices which were officially released running other operating systems.

Android had a worldwide smart phone market share of 75% during the third quarter of 2012, with 500 million devices activated in total and 1.3 million activations per day. The operating system's success has made it a target for patent litigation as part of the so-called "smart phone wars" between technology companies.

Usage share of Android versions:

Version	Code name	Release date	Distribution (December 3, 2012)
4.2	Jelly Bean	11/13/12	0.80%
4.1.x	Jelly Bean	07/09/12	5.90%
4.0.x	Ice Cream Sandwich	12/16/11	27.50%
3.2	Honeycomb	07/15/11	1.20%
3.1	Honeycomb	05/10/11	0.40%
2.3.3–2.3.7	Gingerbread	02/09/11	50.60%
2.3–2.3.2	Gingerbread	12/06/10	0.20%
2.2	Froyo	05/20/10	10.30%
2.0–2.1	Eclair	10/26/09	2.70%
1.6	Donut	09/15/09	0.30%