Android - Refreshing a bit of history

Android was created on 5th November 2007.

Android 1.0 (API level 1)
This is the first commercial release on 23 Sep 2008. The commercial device was HTC Dream.

Android 1.1 (API level 2)
This release was on Feb 2009. The internal code name was Petite Four. but this name was never used publicly. This version contained bug fixes from 1.0 and few minor feature additions

Android 1.5 (Cupcake) (API Level3)
This release was on April 2009. This version was based on Linux Kernel. This is the first release starting with a theme and henceforth followed for subsequent ones.

This version included support for widgets. Bluetooth A2DP profile as major enhancements.

Android 1.6 (Donut) (API Level 4)
Released on Sep 2009.

This release contained few features such as updated technology support for CDMA/EVDO/802.1x

Android 2.0 (Eclair) (API Level 5)
Released on October 2009

This version had Bluetooth 2.1 support, Improved ui, live wallpapers etc.

Android 2.0.1 (Eclair) API level 6
This release was on Dec 2009. With minor API changes, bug fixes and framework behavioral changes.

Android 2.1 (Eclair) API Level 7
released on Jan 2010. This version had Minor API amendments and bug fixes.

Android 2.2 (Froyo) API level 8
This is short form of Frozen Yogurt. this version has additional application speed enhancements using the JIT compiler. This version has the C2DM feature introduced. Has added Wifi hotspot functionality.
Supports bluetooth enabled car and desk docks. Added Adobe flash support

Android 2.3 - 2.3.2 Gingerbread (API level 9)
This was my first android device. Released on Decemeber 2010. This version included updated user interface for simplicity and speed. Native support for SIP and VOIP telephony, support for NFC, support for WebM, VP8 codec and AAC playbacks, concurrent garbage collection for increased performance.

Android 2.3.3 to 2.3.7 (API Level 10)

This version has several improvements and bug fixes. This has improved network performance for Nexus S 4G, This release added support for Google Waller in Nexus 4S phones. 

Android 3.0 HoneyComb (API Level 11)
this was released on February 2011, This version was the first tablet only update. The first device featuring this is Motorola Xoom tablet. This version has simplified multi tasking, Support for multi core processors, https stack improved with server name indication (sni).

Android 3.1 Honey Comb (API Level 12)

Released on May 2011 contains ui enhancements, resizable home screen widgets, support for joystick and gamepads, support for external key boards and pointing devices, support for FLAC audio playback, Support for http proxy for each WiFi access point. 

Android 3.2 Honey comb (API Level 13)

This has versions unto 3.2 to 3.2.6. Released on July 2011. Most first and second generation Google TV devices utilise the Honeycomb 3.2 version. 

Android 4.0 - Android 4.0.2 Ice Cream Sandwich (API Level 14)

Released on Oct 2011. This is the last version that included Adobe's flash player. This version has Android beam, a NFC feature that allows rapid short-range exchange of bookmarks, contact info, directions, youtube videos and other data. 

Includes Web-P image format, WiFi Direct, Android VPN framework (AVF),

Android 4.0.3 - 4.0.4 Ice Cream Sandwich (API Level 15) 

Released on Dec 2011, this version includes new APIs for developers, including social stream social apis in contacts provider, smoother screen rotations, stability improvements 

Android 4.1 Jelly Bean (API Level 16)  

Released on July 2012, Nexus 7 was the first device to run Jelly bean OS. This included ui performance and smoothness, triple buffering, a smoothness project called "Project Butter". 

Android 4.2 Jelly Bean (API Level 17)

Re,eased on Oct 2012, This version is debuted on Google's Nexus 4 and Nexus 10 which were released on Nov 2012.

This supports wireless display from Miracast. 

Android 4.3 Jelly Bean (API Level 18)

This was released on July2013 with the slogan "Ever sweet Jellybean" during an event called breakfast with Sundar Pichai. Nexus 7 tablet was the first device which officially shipped with this OS . This version has Open GL ES3.0 

This version has support for system level Geo fencing and WiFi scanning APIs. Included DRM APIs, Bug fixes for Nexus 7 running on LTE.

Android 4.4 Kitkat (API Level 19)
This version is released on Sep 2013,
Major features include NFC host card emulation, enabling device to replace smart cards.  Webviews are based on Chromium engine, This version has built in screen recording feature. This version has a built in IR blaster.

References:
http://en.wikipedia.org/wiki/Android_version_history