Android is a Linux-based, Open Source Operating System specially designed for touchscreen mobile devices such as smartphones and tablet computers. Android was developed by the Open Handset Alliance : a consortium of hardware, software, and telecommunication companies devoted to advancing open standards for mobile devices, led by Google and other companies.

Android gives you a world-class platform for creating apps and games for Android users everywhere, as well as an open marketplace for distributing to them instantly.

The first beta version of Android Software Development Kit (SDK) was released by Google in 2007 where as the first commercial version, Android 1.0, was released in September 2008. The first Android-powered phone in the market was the G1 device manufactured by HTC, first sold in October 2008.

On July 24, 2013, Google release latest Android version, 4.3 Jelly Bean. Jelly Bean 4.3 is an extended version of Android version, 4.2 Jelly Bean, with Restricted profiles limit access to apps and content, Smart Bluetooth support, 3D realistic, high performance graphics powered by OpenGL ES 3.0, Internationalization and localization with additional language support features.

Features of Android

Features Description
User Interface Android OS provides beautiful and interactive UI, it also provides other UI modules for special interfaces such as dialogs, notifications, and menus.
Handset layouts Android platform is adaptable to larger, VGA, 2D graphics library, 3D Graphics library based on OpenGL ES 2.0 specification, and traditional smartphones layout.
Storage SQLite, a lightweight relational database, is used for data storage purposes.
Connectivity Android supports connectivity technologies including GSM/EDGE, Bluetooth, Wi-Fi, IDEN, CDMA, EV-DO, UMTS, LTE, NFC and WiMAX.
Messaging SMS and MMS are available as forms of messaging, including threaded text messaging and Android Cloud
To Device Messaging (C2DM) and now enhanced version of C2DM, Android Google Cloud Messaging (GCM) is also a part of Android Push Messaging service.
Multiple language support Android supports multiple languages.
Web browser The web browser available in Android is based on the open-source WebKit layout engine, coupled with
Chrome's V8 JavaScript engine.
Java support While most Android applications are written in Java, there is no Java Virtual Machine in the platform and
Java byte code is not executed. Java classes are compiled into Dalvik executables and run on Dalvik,
a specialized virtual machine designed specifically for Android and optimized for battery-powered mobile
devices with limited memory and CPU. J2ME support can be provided via third-party applications.
Media support Android supports the following audio/video/image media formats: MP3, MPEG-4 SP, WebM, H.263, H.264, AAC, HE-AAC
(in 3GP or MP4 container), AMR, AMR-WB (in 3GP container), MIDI, Ogg Vorbis, FLAC,
Streaming media support RTP/RTSP streaming (3GPP PSS, ISMA), HTML progressive download (HTML5 <video> tag).
Adobe Flash Streaming (RTMP) and HTTP Dynamic Streaming are supported by the Flash plugin.
Apple HTTP Live Streaming is supported by RealPlayer for Android, and by the operating
system in Android 3.0 (Honeycomb)
Additional hardware support Android can use video/still cameras, touchscreens, GPS, gyroscopes, barometers, accelerometers,
magnetometers, dedicated gaming controls, proximity and pressure sensors, thermometers, accelerated
2D bit blits (with hardware orientation, scaling, pixel format conversion) and accelerated 3D graphics.
Multi-touch Android has native support for multi-touch which was initially made available in handsets such as the HTC
Hero. The feature was originally disabled at the kernel level (possibly to avoid infringing Apple's patents on
touch-screen technology at the time). Google has since released an update for the Nexus One and the
Motorola Droid which enables multi-touch natively
Bluetooth Supports A2DP, AVRCP, sending files (OPP), accessing the phone book (PBAP), voice dialing and sending
contacts between phones. Keyboard, mouse and joystick (HID) support is available in Android 3.1+, and
in earlier versions through manufacturer customizations and third-party applications
Video calling Android does not support native video calling, but some handsets have a customized version of the
operating system that supports it, either via the UMTS network (like the Samsung Galaxy S) or over IP.
Video calling through Google Talk is available in Android 2.3.4 and later. Gingerbread allows Nexus S
to place Internet calls with a SIP account. This allows for enhanced VoIP dialing to other SIP accounts
and even phone numbers. Skype 2.1 offers video calling in Android 2.3, including front camera support.
Users with the Google+ android app can video chat with other google+ users through hangouts.
Multitasking Multitasking of applications, with unique handling of memory allocation, is available
Accessibility Built in text to speech is provided by Talk back for people with low or no vision. Enhancements for
people with hearing disabilities is available as is other aids.
Voice based features Google search through voice has been available since initial release. Voice actions for calling, texting,
navigation, etc. are supported on Android 2.2 onwards. As of Android 4.1, Google has expanded Voice
Actions with the ability to talk back and read answers from Google's Knowledge Graph when queried with
specific commands. The ability to control hardware has not yet been implemented.
Tethering Android supports tethering, which allows a phone to be used as a wireless/wired Wi-Fi hotspot.
Before Android 2.2 this was supported by third-party applications or manufacturer customizations.
Screen capture Android supports capturing a screenshot by pressing the power and volume-down buttons at the same
time. Prior to Android 4.0, the only methods of capturing a screenshot were through manufacturer
and third-party customizations or otherwise by using a PC connection (DDMS developer's tool).
These alternative methods are still available with the latest Android.
External storage Most Android devices include microSD slot and can read microSD cards formatted with FAT32, Ext3 or Ext4
file system. To allow use of high-capacity storage media such as USB flash drives and USB HDDs, many
Android tablets also include USB 'A' receptacle. Storage formatted with FAT32 is handled by Linux Kernel
VFAT driver, while 3rd party solutions are required to handle other popular file systems such as NTFS, HFS
Plus and exFAT.