Android 4.2 is an incremental update in the "Jelly Bean" version series which debuted with the Nexus 4 and Nexus 10. Please only use this tag if you feel your question is specific to Android 4.2.
Released in November 2012, Android 4.2 is an incremental update to Android 4.1 which maintains the "Jelly Bean" moniker. It was launched on the Nexus 4 phone and Nexus 10 tablet, and introduced several notable new features, including:
- Gesture typing (similar to Swype)
- Multiple user accounts on tablets
- The ability to display certain widgets on the lockscreen
- Photo Sphere camera mode
- Native support for Miracast
The full release notes can be found on the Android Developers site.