Android (operating system)4.2 BY Google.

Android (operating system)4.2 BY Google.

Android is a Linux-based operating system designed primarily for touchscreen mobile devices such assmartphones and tablet computers. Initially developed by Android, Inc., whom Google financially backed and later purchased in 2005,^[9] 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.^[10] The first Android-powered phone was sold in October 2008.^[11]

Android is open source and Google releases the code under the Apache License.^[12] 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 Javaprogramming language.^[13] 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.

Android

Android 4.2 "Jelly Bean" on the Nexus 4
Company / developer	Google Open Handset Alliance Android Open Source Project
Programmed in	C, C++, Java[1]
OS family	Unix-like
Working state	Current
Source model	Open source[2]
Initial release	September 23, 2008[3]
Latest stable release	4.2.1 Jelly Bean / November 27, 2012; 45 days ago[4][5]
Marketing target	Smartphones Tablet computers
Available language(s)	Multi-lingual
Package manager	Google Play, APK
Supported platforms	ARM, MIPS,[6] x86[7]
Kernel type	Monolithic (modified Linux kernel)
Default user interface	Graphical (Multi-touch)
License	Apache License 2.0 Linux kernel patches under GNU GPL v2[8]
Official website      www.android.com

Interface

Android's user interface is based on direct manipulation,^[35] using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching and reverse pinching to manipulate on-screen objects.^[35] The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide haptic feedback to the user. Internal hardware such as accelerometers, gyroscopes and proximity sensors are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel.^[36]

Android devices boot to the homescreen, the primary navigation and information point on the device, which is similar to thedesktop found on PCs. Android homescreens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content such as the weather forecast, the user's email inbox, or a news ticker directly on the homescreen.^[37] A homescreen may be made up of several pages that the user can swipe back and forth between, though Android's homescreen interface is heavily customisable, allowing the user to adjust the look and feel of the device to their tastes. Third party apps available on Google Play and other app stores can extensively re-theme the homescreen, and even mimic the look of other operating systems, such as Windows Phone.^[38] Most manufacturers, and some wireless carriers, customise the look and feel of their Android devices to differentiate themselves from the competition.

Present along the top of the screen is a status bar, showing information about the device and its connectivity. This status bar can be "pulled" down to reveal a notification screen where apps display important information or updates, such as a newly received email or SMS text, in a way that doesn't immediately interrupt or inconvenience the user.^[39] In early versions of Android these notifications could be tapped to open the relevant app, but recent updates have provided enhanced functionality, such as the ability to call a number back directly from the missed call notification without having to open the dialer app first.^[40]Notifications are persistent until read or dismissed by the user.

Applications

Play Store on the Galaxy Nexus.

See also: Android software development and Google Play

Android has a growing selection of third party applications, which can be acquired by users either through an app store such asGoogle Play or the Amazon Appstore, or by downloading and installing the application's APK file from a third-party site.^[41] The Play Store application allows users to browse, download and update apps published by Google and third-party developers, and is pre-installed on devices that comply with Google's compatibility requirements.^[42] The app filters the list of available applications to those that are compatible with the user's device, and developers may restrict their applications to particular carriers or countries for business reasons.^[43] Purchases of unwanted applications can be refunded within 15 minutes of the time of download,^[44] and some carriers offer direct carrier billing for Google Play application purchases, where the cost of the application is added to the user's monthly bill.^[45] As of September 2012, there were more than 675,000 apps available for Android, and the estimated number of applications downloaded from the Play Store was 25 billion.^[46]

Applications are developed in the Java language using the Android software development kit (SDK). The SDK includes a comprehensive set of development tools,^[47] including a debugger, software libraries, a handset emulator based on QEMU, documentation, sample code, and tutorials. The officially supported integrated development environment (IDE) is Eclipse using the Android Development Tools (ADT) plugin. Other development tools are available, including a Native Development Kit for applications or extensions in C or C++, Google App Inventor, a visual environment for novice programmers, and various cross platform mobile web applications frameworks.

In order to work around limitations on reaching Google services due to Internet censorship in the People's Republic of China, Android devices sold in the PRC are generally customized to use state approved services instead.^[48]

Usage share of Android versions

Usage share of the different versions as of December 3, 2012

Usage share of the different versions as of December 3, 2012.^[132] Most Android devices to date still run the older OS version 2.3 Gingerbread that was released on December 6, 2010, due to most lower-end devices still being released with it.

Version	Code name	Release date	API level	Distribution (December 3, 2012)
4.2	Jelly Bean	November 13, 2012	17	0.8%
4.1.x	Jelly Bean	July 9, 2012	16	5.9%
4.0.x	Ice Cream Sandwich	December 16, 2011	15	27.5%
3.2	Honeycomb	July 15, 2011	13	1.2%
3.1	Honeycomb	May 10, 2011	12	0.4%
2.3.3–2.3.7	Gingerbread	February 9, 2011	10	50.6%
2.3–2.3.2	Gingerbread	December 6, 2010	9	0.2%
2.2	Froyo	May 20, 2010	8	10.3%
2.0–2.1	Eclair	October 26, 2009	7	2.7%
1.6	Donut	September 15, 2009	4	0.3%
1.5	Cupcake	April 30, 2009	3	0.1%

Beyond smartphones and tablets

The Sony SmartWatch: an example of how Android is used on electronics other than smartphones and tablets

The open and customizable nature of Android allows it to be used on other electronics, including laptops and netbooks,smartbooks^[150] smart TVs (Google TV) and cameras (Nikon Coolpix S800c).^[151][152] In addition, the Android operating system has seen applications on smart glasses (Project Glass), wristwatches,^[153] headphones,^[154] car CD and DVD players,^[155] mirrors,^[156] portable media players^[157] and landlines.^[158] Ouya, an upcoming videogames console running Android, became one of the most successful Kickstarter campaigns, crowdfunding US$8.5m for its development.^[159][160]

In 2011, Google demonstrated "Android@Home", a new home automaton technology which uses Android to control a range of household devices including light switches, power sockets and thermostats.^[161] Prototype light bulbs were announced that could be controlled from an Android phone or tablet, but Android head Andy Rubin was cautious to note that "turning a lightbulb on and off is nothing new," pointing to numerous failed home automation services. Google, he said, was thinking more ambitiously and the intention was to use their position as a cloud services provider to bring Google products into customers' homes.^[162]

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