Android is a mobile operating system based on Debian, first developed by Android Inc and then a combined effort with Google. It is a participant in the Open Handset Alliance, with a focus on ease of use.
Android has a large community of developers writing apps that extend the functionality of devices. There are many apps available for Android, produced with a mobile development environment.
Android Market is the online app store run by Google, though apps can be downloaded from third party sites. Google released most of the Android code under the Apache License, a free software and open source license.