Please only use this tag if you feel your question is specific to Android 4.4 -- the 9th publicly named Android release which debuted with the Nexus 5 in October 2013
Android 4.4 KitKat was announced on October 31, 2013 along with the Nexus 5, the first device to ship with this version of Android. Much of the focus of KitKat was on ensuring that Android would run as smoothly as possible even on lower-end devices, targeting those with 512 MB of RAM as a starting point. Other features include:
- Host Card Emulation for NFC-enabled devices
- A new printing framework
- A new storage access framework
- Improvements to sensor management and support for new sensors
An overview of the new platform features can be found on the Android Developers site.