Android is a software stack for mobile devices including an operating system, middleware and key applications. It is being developed by the Open Handset Alliance, a group of more than 30 technology and mobile companies. Android was built from the ground-up to enable developers to create compelling mobile applications that take full advantage of all a handset has to offer. Developers can create applications for the platform using the Android SDK.
Reference:
http://code.google.com/android/
