The document discusses several mobile operating systems including iOS, Android OS, Windows Mobile, Symbian, and Blackberry OS. iOS is Apple's proprietary OS used on iPhones and iPads. Android OS is an open-source Linux-based OS developed by Google. Windows Mobile is Microsoft's mobile OS. Symbian and Blackberry OS were previously popular but have lost market share to iOS and Android. Each OS has advantages like stability, interface, hardware integration, and app availability as well as disadvantages like being proprietary, crashes, or lacking apps.