This document discusses mobile operating systems. It introduces various operating systems used in mobile devices including Android, BlackBerry OS, iOS, Symbian OS, Windows Phone OS, Bada, and Asha. It provides details on the history and key features of each operating system. It also includes market share data and examples of popular smartphones that run on each operating system. The document concludes that the mobile field continues to rapidly develop with new features introduced with each OS update due to high competition.