In September 2008, Google released the first version of Android, a new smartphone operating system, as open source (some Google applications that are sometimes but not always bundled with Android are not open source). Initially, the operating system was given away for free by Google, and was eagerly adopted by many handset makers; Google later bought Motorola Mobility and produced its own "vanilla" Android phones and tablets, while continuing to allow other manufacturers to use Android. Android is now the world's most popular mobile platform.