Android is an open-source, Linux-based operating system for mobile devices like smartphones and tablets. It was developed by Android Inc, which was acquired by Google in 2005. The Android operating system allows users to run multiple apps simultaneously, supports graphics and 3D capabilities, and provides access to over 400,000 apps in the Android Market. Some key versions of Android include 1.0, 2.0, 3.0 and 4.0. Compared to the iPhone OS, Android provides more flexibility in customization, easier syncing with computers, and support for technologies like Flash.