The version of iOS (formerly iPhone OS) that was released by Apple on 7 Mar 2012. iOS 5.1 runs on iPhone 3GS (and newer), iPad 1 (and newer), iPod Touch 3rd generation (and newer).
iOS 5.1 was released on March 7, 2012. It supports the same devices as iOS 5 and was the initial release for the iPad 3. Also see ios and ios5 for more information.
Version 5.1 added new features to the Camera, Clock, Safari, and Photos. Many bug fixes and minor changes were also made to Maps, Phone, Music, Video, and Siri. This update also addressed security issues, network compatibility / features, and some settings.