Different companies use different code names for their operating system upgrades. Sometimes the code names are even used to mark the upgrade. Apple has gone with a large cat theme for OSX, with names like Snow Leopard and Mountain Lion. Ubuntu Linux uses an alliterative adjective + animal combination for things like Breezy Badger and Lucid Lynx. Red Hat Linux has releases with names that seemed to all over the place.
Google has gone with an alphabetical list of sweets. A and B were apparently reserved for alpha and beta releases and not given a public code name.
The first release of Android on a commercial phone was the T-Mobile G1 by HTC, and it ran Android 1.0, which was upgraded to 1.1 for some minor bug fixes. It did not have a code name.
The basic features included:
- Ability to download apps through the Android Market
- Web Browser
- Google Maps
- Google Search
- Home screen widgets
It did not include multitouch, easy syncing with Exchange email accounts, the ability to run Flash, or support for security features found in corporate phones.
Now, once that very basic phone was released, the alphabetical sweets names began to kick into action. Each time a new version of the operating system was released, Google would also unveil a new sculpture in their Mountain View, California headquarters.
Android 1.5 This version of Android was the first major upgrade to be sent to phones over the air. It fixed a pile of issues with email and added support for the Bluetooth stereo profile. There were also some speed and Web browser improvements. Most importantly, Cupcake allowed widget development.
Android 2.0 was released in 2009, and this upgrade introduced Google's speech synthesis through "talk back." It also integrated location services into other apps and added things like transit directions in a much-improved Google Maps. Donut also added CDMA support, which allowed Sprint and Verizon to begin supporting the phone.
Android 2.1 doesn't seem like a huge leap, and it wasn't, but it did allow multiple email accounts, upgraded Bluetooth profiles, an improved Calendar app that allowed you to respond to and create event invitations, and new "live wallpapers" that moved in the background (and drained batteries pretty fast.)
Android 2.2 was a heavily anticipated upgrade in May of 2010. It went first to the Nexus One and then to other phones that supported it. Froyo offered a lot of speed improvements, voice recognition for voice dialing and Google commands, and hotspot tethering. Froyo also added pinch to zoom and other multitouch gestures that Google had previously avoided out of fear of Apple reprisal.
Android 2.3 was released in December 2010, and it changed the user interface to a green color scheme. It also added support for NFC (Near Field Communication) and support for front facing cameras. The upgrade was also a big improvement on battery life and speed.
Android 3.0 was also highly anticipated, but this release only went to tablets. Honeycomb introduced the all software button approach Google is now favoring in all Android phones, and the interface introduced the Action Bar and System Bar along with a way to handle deeper menus on tablets.
Ice Cream Sandwich
Android 4.0 was targeted at phones and released in October 2011, although it has yet to hit all phones theoretically capable of the upgrade. This version was intended to bring the new and different Honeycomb tablet over to phones. It was also intended to make development easier in a fragmented market.
Android 5.0? This release has not yet hit the world, although it's very likely to do so in the summer of 2012. Only the name has been confirmed at this writing, and the version number could be lower. This version will probably support Chrome as the native browser app, replacing the Webkit-based browser in previous versions, and it may have built-in file management and a lightweight version for use on cheaper hardware.
Key Lime Pie
This is pure speculation, but it's the most popular rumored name for the version of Android to follow Jelly Bean. Since it's hard to think of any other names for sweets that start with K, I think this is probably a safe bet.