Android OS Release History

1.5 Cupcake
It was the first major update to Android that supported devices other than the G1.
for more details:
Android 1.5 Highlights
Changelog:

• MMS - New Features
• E-mail - Significant bug fixes
• Alarm Clock - Significant bug fixes
• Package Installer - Significant bug fixes
• Settings - New features
• Music - New features
• Browser - New features
• VoiceDialer - New features
• Camera/Gallery - New features
• Download manager - New features
• Framework - New features + Significant bug fixes
• Bluetooth - New features + Significant bug fixes
• System software - New features
• Radio & Telephony - New features

----------------

1.6 Donut
for more details:
Android 1.6 Highlights
Changelog:

• Quick Search Box for Android
• Camera, Camcorder, and Gallery
• VPN, 802.1x
• Battery usage indicator
• Accessibility
• Expanded Search Framework
• Text-to-speech engine
• Gestures
• Accessibility
• Expanded support for screen densities and resolutions
• Telephony support for CDMA
• New version of OpenCore
• 2.6.29 Linux kernel

----------------

2.0/2.1 Eclair
for more details:
Android 2.0 Highlights
Changelog:

• Account manager API
• Sync adapter API
• Quick contact
• Unified inbox with support for
• o multiple Google/Gmail accounts
• o Microsoft Exchange/Activesync accounts
• o Facebook
• New Bluetooth API
• HTML5 compatible browser
• Overhauled camera app
• Improved accuracy and usability of onscreen keyboard
• Additional screen resolutions and sizes
• Updated UI
• New Gallery app
• Live wallpapers
• New News/weather widget

----------------

2.2 Froyo
for more details:
Android 2.2 Highlights
Changelog:

• JIT (Just in Time) Compiler
  o 2 to 2.5 times faster due to JIT compiler.
• Enterprise
  o Microsoft Exchange friendly!
  o New APIs for device management - remote wipe, etc.
• browser enhancements
  o 2-3 x performance improvement (Chrome JS engine) "World's Fastest Mobile Browser"
• Application data backup API, in addition to the installed applications backup
• Cloud to phone API (Send intents from PC browser to phone)
• Android Market improvements
  o Improved search
  + (Quick search)
  + Search from within app data
  + Official Apps on SD card support
  + "Update all apps"
  + Optional auto-update of all apps
  + Crash reporting API
• Macromedia/Adobe Flash 10.1 support
• Internet connection sharing
  o Tethering to a single PC over USB or Bluetooth
  o Mobile WiFi hotspot/router
• Separation of core OS and Google apps
• Stagefright
• 2.6.32 kernel upgrade
  + HIGHMEM support for RAM >256MB
  + SDIO scheduling and BT improvements

----------------

2.3 Gingerbread]
for more details:
Android 2.3 Highlights
Changelog:

• UI refinements for simplicity and speed
• Faster, more intuitive text input
• One-touch word selection and copy/paste
• Improved power management
• Control over applications
• New ways of communicating, organizing
  o Internet calling
  o Near-field communications
• Downloads management
• Enhancements for gaming
• New forms of communication
  o Internet telephony
  o Near Field Communications (NFC)turers.
• Rich multimedia
• Media Framework
  o New media framework fully replaces OpenCore, maintaining all previous codec/container support for encoding and decoding.
  o Integrated support for the VP8 open video compression format and the WebM open container format
  o Adds AAC encoding and AMR wideband encoding
• Linux Kernel upgraded to 2.6.35
• Networking
  o SIP stack, configurable by device manufacturer
  o Support for Near Field Communications (NFC), configurable by device manufacturer
  o Updated BlueZ stack
• Dalvik runtime improvements

----------------

3.0 Honeycomb
Exclusive to Tablets
for more details:
Android 3.0 Highlights
Changelog:

• Optimized tablet support with a new user interface
• Three dimensional desktop with redesigned widgets
• Refined multi-tasking
• Browser enhancements
• Support for video chat using Google Talk
• Hardware acceleration
• Support for multi-core processors

----------------

4.0 Ice Cream Sandwich
Android 4.0 Highlights
Changelog:

• Virtual buttons in the UI, in place of capacitive or physical buttons
• Separation of widgets in a new tab, listed in a similar list to apps
• Easier-to-create folders, with a drag-and-drop style
• A customizable launcher
• Improved visual voicemail with the ability to speed up or slow down voicemail messages
• Pinch-to-zoom functionality in the calendar
• Offline search, a two-line preview, and new action bar at the bottom of the Gmail app
• Ability to swipe left or right to switch between Gmail conversations
• Integrated screenshot capture (accomplished by holding down the Power and Volume-Down buttons)
• Improved error correction on the keyboard
• Ability to access apps directly from lock screen (similar to the HTC Sense 3.x)
• Improved copy and paste functionality
• Better voice integration and continuous, real-time speech to text dictation
• Face Unlock, a feature that allows users to unlock handsets using facial recognition software
• New tabbed web browser, allowing up to 16 tabs
• Automatic syncing of browser with users' Chrome bookmarks
• Modern Roboto font
• Data Usage section in settings that lets users set warnings when they approach a certain usage limit, and disable data when the limit is exceeded
• Ability to shut down apps that are using data in the background
• Improved camera app with zero shutter lag, time lapse settings, panorama mode, and the ability to zoom while recording
• Built-in photo editor
• New gallery layout, organized by location and person
• Refreshed 'People' app with social network integration, status updates and hi-res images
• Android Beam, a NFC feature that lets user exchange web bookmarks, contact info, directions, YouTube, etc.
• Hardware acceleration of the UI
• Resizeable widgets, already part of 3.1 but new for cellphones
• Wi-Fi Direct[60]
• 1080p video recording for stock android