-ANDROID CODENAMES-

'Astro Boy' 'R2-D2' 'Bender' may have been pre-milestones to the first official 1.0 version release.

- Alpha - Android v1.0 no code name, unless you count 'OMG'

- Petit Four / Beta - v1.1 -Debuted November 5, 2007 - Android's official birthday

- Cupcake - v1.5 - Debuted October 2008
Key additions: Speech recognition tools, a virtual keyboard, video upload support for YouTube and support for live data feeds and live folders.

- Donut- v1.6 - Debuted in Fall 2009
Key additions: Support for CDMA smartphones, additional screen sizes and a text-to-speech engine.

- Eclair - v2.0 v2.0.1 v2.1 - Debuted October 2009
Key additions: Support for multi-touch devices, new browser interface, Microsoft Exchange support, single interface for managing multiple online accounts, soft keys support, and an enhanced camera app (with digital zoom and flash support).

- FroYo - 'Frozen Yoghurt' v2.2 - Debuted October 2010
Key additions: USB tethering support (for turning a smartphone into a Wi-Fi hotspot), significant speed improvements, Flash 10.1 support, voice dialing over Bluetooth, the ability to store apps on external memory cards, updated browser with Google Chrome's V8 JavaScript.

- Gingerbread - v2.3 v2.3.2 v2.3.3 v2.3.7 - Debuted December 2010
Key additions: Google Voice over Wi-Fi, enhanced gaming functionality, improved Google Apps.

- Honeycomb - v3.0 v3.1 v3.2x - Debuted February 2011
Key additions: A tablet-centric update that delivered a new interface optimized for devices with larger screen sizes (particularly tablets), video chat support based on Google Talk protocols, new System Bar for global status and notifications and Action Bar for application control, tabbed Web browsing, optimized soft keyboard and a new email interface.

- IceCream Sandwich - v4.0 v4.0.1 v4.0.2 v4.0.3 v4.0.4 - Debuted October 2011
Key additions: A smartphone-centric update based on the Linux kernel v3.0.1 that brings many of Honeycomb's features to smartphones, including Face Unlock facial recognition software, tabbed Web browsing capabilities, unified social networking contacts, 1080p video recording capabilities and video chat support based on Google Talk protocols.

- JellyBean - v4.1 and v4.2 and v4.3 - Debuted June 2012
4.2.3 Jellybean mobile operating system works on tablet, mobile phone, tvsetbox all android only devices. Not for Desktops or Lapstops.
Key additions: Advanced natural language voice command capabilities akin to Apple's Siri, enhanced interface and overall responsiveness via "Project Butter," Google Now support, an improved Web browser, enhanced file management capabilities and more.

- KitKat - v4.4 v4.4.4 *Originally was to be code-named Key Lime Pie) - Debuted as KitKat November 2013
Key additions: Full-screen immersive mode, new transitions framework, and "Project Svelte," a project initiated to reduce the memory needs of the Android OS. Originally internally referred to as Key Lime Pie, Google announced in early September 2013 that it would be using the iconic candy bar as the codename for the 4.4 Android release.

- Lollipop - v5.0 v5.1 - Debuted November 2014
Key additions: Enhanced Material Design user interface, improved continuity across Android devices, multiple user support, a guest user account option, a new notification system, support for 64-bit CPUs, and more.

- Marshmallow - v6.0 - Debuted November 2015
Key additions: Now on Tap functionality and other Google Now enhancements, native fingerprint authentication support, Android Pay integration, USB Type-C support, improved battery life, better app management and more.

- Nougat - v7.0 v7.1 - Debuted in September 2016
Key additions: Split Screen for true multitasking, Doze on the Go for conserving battery power, Notification Direct Reply and Bundled Notifications, new security features, a Data Saver mode and more.




Code:
https://source.android.com/source/build-numbers