ANDROID
Technologically, Android includes middleware and key applications, and uses a modified version of the Linux kernel. It was initially developed by Android Inc., a firm later purchased by Google, and lately by the Open Handset Alliance. It allows developers to write managed code in the Java language, controlling the device via Google-developed Java libraries
The Android operating system software stack consists of Java applications running on a Java based object oriented application framework on top of Java core libraries running on a Dalvik virtual machine featuring JIT compilation. Libraries written in C include the surface manager, OpenCore media framework, SQLite relational database management system, OpenGL ES 2.0 3D graphics API, WebKit layout engine, SGL graphics engine, SSL, and Bionic libc. The Android operating system consists of 12 million lines of code including 3 million lines of XML, 2.8 million lines of C, and 2.1 million lines of Java.

VERSIONS:

1.5 (Cupcake)

Devices that have 1.5 as OEM OS - HTC hero , Motorola DEXT , Samsung Galaxy Portal , Samsung I 7500 , T-mobile G1 , LG InTouch GW620 , Dell Aero

Based on Linux Kernel 2.6.27 On 30 April 2009, the official 1.5 (Cupcake) update for Android was released. There were several new features and UI updates included in the 1.5 update:
Ability to record and watch videos through camcorder mode
Uploading videos to YouTube and pictures to Picasa directly from the phone
A new soft-keyboard with text-prediction
Bluetooth A2DP and AVRCP support
Ability to automatically connect to a Bluetooth headset within a certain distance
New widgets and folders that can populate the Home screens
Animated screen transitions

1.6 (Donut)

Devices that have 1.6 as OEM OS - Acer Liquid , Sony Ericsson Xperia X10 , HTC tattoo , Kyocera Zio M6000

Based on Linux Kernel 2.6.29 On 15 September 2009, the 1.6 (Donut) SDK was released. Included in the update were:
An improved Android Market experience
An integrated camera, camcorder, and gallery interface
Gallery now enables users to select multiple photos for deletion
Updated Voice Search, with faster response and deeper integration with native applications, including the ability to dial contacts
Updated search experience to allow searching bookmarks, history, contacts, and the web from the home screen
Updated technology support for CDMA/EVDO, 802.1x, VPNs, and a text-to-speech engine
Support for WVGA screen resolutions
Speed improvements in searching and camera applications
Gesture framework and GestureBuilder development tool

2.0/2.1 (Eclair)

Devices that have 2.0 as OEM OS - Motorola Milestone , LG GT540 , GW880 Ophone
Devices that have 2.1 as OEM OS - Google Nexus One , HTC Desire , HTC Legend , T-Mobile Pulse , HTC EVO , Samsung Fascinate , Samsung Intercept , HTC Vision , Motorola Charm , HTC Aria , HTC Wildfire , Samsung Galaxy Beam , Samsung Vibrant , Samsung Galaxy S Pro , LG Ally , LG LU2300 , Droid X , Vodafone 845 , Dell Thunder


Based on Linux Kernel 2.6.29 On 26 October 2009 the 2.0 (Eclair) SDK was released. Included in the update were:
Optimized hardware speed
Support for more screen sizes and resolutions
Revamped UI
New Browser UI and HTML5 support
New contact lists
Better white-black ratio for backgrounds
Improved Google Maps 3.1.2
Microsoft Exchange support
Built in flash support for Camera
Digital Zoom
MotionEvent class enhanced to track multi-touch events
Improved virtual keyboard
Bluetooth 2.1
Live Wallpapers
The 2.0.1 SDK was released on 3 December 2009.
The 2.1 SDK was released on 12 January 2010.

2.2 (Froyo)

Devices that have 2.2 as OEM OS - Optimus One , LG Optimus Chic , HTC Scorpion , Dell Smoke

Based on Linux Kernel 2.6.32 On 20 May 2010 the 2.2 (Froyo) SDK was released. Changes included:[49]
General Android OS speed, memory, and performance optimizations
Additional application speed improvements courtesy of JIT implementation
Integration of Chrome's V8 JavaScript engine into the Browser application
Increased Microsoft Exchange support (security policies, auto-discovery, GAL look-up, calendar synchronization, remote wipe)
Improved application launcher with shortcuts to Phone and Browser applications
USB tethering and WiFi hotspot functionality
Added an option to disable data access over mobile network
Updated Market application with batch and automatic update features[
Quick switching between multiple keyboard languages and their dictionaries
Voice dialing and contact sharing over Bluetooth
Support for numeric and alphanumeric passwords
Support for file upload fields in the Browser application
Support for installing applications to the expandable memory
Adobe Flash 10.1 support

3,0 (Gingerbread)

Based on Linux Kernel 2.6.33 or 34 Tentatively scheduled for Q4 2010 launch. Confirmed new features:
Support for WebM video playback
Improved copy–paste functionalities
Unconfirmed new features:
Android Market music store
Media streaming from PC library
Revamped UI
Support for bigger screens with up to