A Linux-based operating system for smartphones and tablet computers. Unless the question is specifically regarding the device interacting with your computer questions are more likely to be better suited to android.stackexchange.com. For programming Android applications there is stackoverflow.com.
Android is an operating system for smart phones and other mobile devices. Primarily developed and distributed by Google, Android is an open source operating system based on a modified version of the Linux kernel.
Operating system for mobile devices. Developed by Google and the Open Handset Alliance.
Android page on Wikipedia
Detailed information about the Android OS.
General information about the Android OS.
Google I/O developer conference
Contains detailed videos and slides by Android product engineers