Android is a Linux based mobile device operating system developed by the Open Handset Alliance led by Google. Android is mainly used in Smartphone and tablet computers. Android is open source ie its features can be extended to incorporate new technologies as they emerge.

Android, Inc. was founded by Andy Rubin, Rich Miner, Nick Sear and Chris White in Palo Alto, California. On August 17, 2005 Google acquired Android Inc. making it a subsidiary of Google Inc.

On November 5, 2007, the Open Handset Alliance publicly announced their first product, Android, a mobile device platform built on Linux kernel version 2.6.

Android provides a broad spectrum of applications and services to its user. Users can fully customize their mobile phones to their interests. The first Mobile phone that has used Android was the HTC Dream, release on 22 October 2008.

Here are some features of Android Operating System .

1. Layout : The layout is primarily based on VGA, 2D graphics library and 3D graphics library based on OpenGL ES 2.0.
2. Storage : For data storage SQLite is used.
3. Connectivity : Android supports GSM / EDGE, IDEN, CDMA, EV-DO, UMTS, Bluetooth, WI-Fi, LTE, NFC and WiMAX connectivity technologies.
4. Multi Lingual Support : It supports multiple languages.
5. Messaging : Android supports SMS and MMS including threaded text messaging and Cloud to Device Messaging (C2DM).
6. Web Browser : It is mainly based on the open-source WebKit layout engine and Chrome's V8 JavaScript engine.
7. Java Support : Most of the applications are written in Java but they run on Dalvik, a specialized virtual machine specifically designed for Android.
8. Media Support : Android supports WebM, H.263, H.264, MPEG-4 SP, AMR, AMR-WB, AAC, HE-AAC, MP3, MIDI, Ogg Vorbis and WebP media formats.
9. Hardware Support : It can support wide variety of hardwares including video / still cameras, touchscreens, GPS, accelerometers, gyroscopes, barometers, magnetometers, dedicated gaming controls, proximity and pressure sensors, thermometers, accelerated 2D bit blits and accelerated 3D graphics.
10. Multitasking : Android supports multitasking.
11. Multi-touch : It supports multi touch natively, but previously it was disabled at the kernel level. An update was released by Google which enables multi-touch natively.
12. External Support : Now the majority of Android devices support microSD slot and can read microSD card formatted with FAT32, Ext3fs or Ext4fs file system.

There are millions of applications available for Android which can be downloaded from Google Play, formerly Android Market. The latest version that is available to phones is Android 4.0.4 Ice Cream Sandwich.