Android Operating System

Android is a Linux based operating system for mobile devices such as smartphones and tablet computers. It is developed by the Open Handset  Alliance led by Google.

Google purchased the initial developer of the software, Android Inc., in 2005. The unveiling of the Android distribution in 2007 was announced with the founding of the Open Handset Alliance, a consortium of 84 hardware, software, and telecommunication companies devoted to advancing open standards for mobile devices. Google releases the Android code as open-source, under the Apache License. The Android Open Source Project (AOSP) is tasked with the maintenance and further development of Android.

Android has a large community of developers writing applications ("apps") that extend the functionality of the devices. Developers write primarily in a customized version of Java. As of October 2011 there were more than 400,000 apps available for Android, and the estimated number of applications downloaded from the Android Market as of December 2011 exceeded 10 billion. Apps can be downloaded from third-party sites or through online stores such as Android Market, the app store run by Google.

Android was listed as the best-selling smartphone platform worldwide in Q4 2010 by Canalys^, with over 200 million Android devices in use by November 2011. According to Google's Andy Rubin, as of December 2011 there are over 700,000 Android devices activated every day.

 Open Handset Alliance

On November 5, 2007, the Open Handset Alliance, a consortium of several companies which include Broadcom Corporation, Google, HTC, Intel, LG, Marvell Technology Group, Motorola, Nvidia, Qualcomm, Samsung Electronics, Sprint Nextel, T-Mobile and Texas Instruments unveiled itself. The goal of the Open Handset Alliance is to develop open standards for mobile devices. On the same day, the Open Handset Alliance also unveiled their first product, Android, a mobile device platform built on the Linux kernel version 2.6.

On December 9, 2008, 14 new members joined, including ARM Holdings, Atheros Communications, Asustek Computer Inc, Garmin Ltd, Huawei Technologies, PacketVideo, Softbank, Sony Ericsson, Toshiba Corp, and Vodafone Group Plc.

Version history 

Android has seen a number of updates since its original release, each fixing bugs and adding new features. Each version is named, in alphabetical order, after a dessert.

Recent releases

§  2.3 Gingerbread refined the user interface, improved the soft keyboard and copy/paste features, improved gaming performance, added SIP support (VoIP calls), and added support for Near Field Communication.

§  3.0 Honeycomb was a tablet-oriented release which supports larger screen devices and introduces many new user interface features, support for multi-core processors, hardware acceleration for graphics and full system encryption. The first device featuring this version, the Motorola Xoom tablet, went on sale in February 2011.

§  3.1 Honeycomb, released in May 2011, added support for extra input devices, USB host mode for transferring information directly from cameras and other devices, and the Google Movies and Books apps.

§  3.2 Honeycomb, released in July 2011, added optimization for a broader range of screen sizes, new "zoom-to-fill" screen compatibility mode, loading media files directly from SD card, and an extended screen support API. Huawei MediaPad is the first 7 inch tablet to use this version 

§  4.0 Ice Cream Sandwich, announced on October 19, 2011, brought Honeycomb features to smartphones and added new features including facial recognition unlock, network data usage monitoring and control, unified social networking contacts, photography enhancements, offline email searching, app folders, and information sharing using NFC. Android 4.0.3 Ice Cream Sandwich is the latest Android version that is available to phones. The source code of Android 4.0.1 was released on November 14, 2011.

Android Market

Android Market is the online software store developed by Google for Android devices. An application program("app") called "Market" is preinstalled on most Android devices and allows users to browse and download apps published by third-party developers, hosted on Android Market. As of October 2011 there were more than 300,000 apps available for Android, and the estimated number of applications downloaded from the Android Market as of December 2011 exceeded 10 billion. The operating system itself is installed on 130 million total devices.

Only devices that comply with Google's compatibility requirements are allowed to preinstall Google's closed-source Android Market app and access the Market. The Market filters the list of applications presented by the Market app to those that are compatible with the user's device, and developers may restrict their applications to particular carriers or countries for business reasons. 

Google has participated in the Android Market by offering several applications themselves, including Google Voice (for the Google Voice service), Sky Map (for watching stars), Finance (for their finance service), Maps Editor (for their MyMaps service), Places Directory (for their Local Search), Google Goggles that searches by image, Gesture Search (for using finger-written letters and numbers to search the contents of the phone), Google Translate, Google Shopper, Listen for podcasts and My Tracks, a jogging application. In August 2010, Google launched "Voice Actions for Android", which allows users to search, write messages, and initiate calls by voice.

Alternatively, users can install apps directly onto the device if they have the application's APK file or from third party app stores such as theAmazon Appstore, 

Version

Distribution	API level	%
4.0.x Ice Cream Sandwich	14-15	0.6%
3.x.x Honeycomb	11-13	3.3%
2.3.x Gingerbread	9-10	55.5%
2.2 Froyo	8	30.4%
2.1 Eclair	7	8.5%
1.6 Donut	4	1.1%
1.5 Cupcake	3	0.6%

There were two more internal releases, called "Astro" and "Bender". The code names are in alphabetical order, and were allegedly changed from robots to desserts to avoid trademark issues.