iOS 5 is the fifth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 4. It was announced at the company's Worldwide Developers Conference on June 6, 2011, and was released on October 12, 2011. It was succeeded by iOS 6 on September 19, 2012.
iOS 5 revamped notifications, adding temporary banners that appear at the top of screen and introducing the Notification Center, a central location for all recent notifications.
The operating system also added iCloud, Apple's cloud storage service for synchronization of content and data across iCloud-enabled devices, and iMessage, Apple's instant messaging service.
For the first time, system software updates could be installed wirelessly, without requiring a computer and iTunes. iOS 5 also featured deep integration with Twitter, introduced multitasking gestures on iPads, and added an easily accessible camera shortcut from the lock screen.
iOS 5 was the subject of criticism for iPhone 4S users, as the initial release had poor battery life, failures of SIM cards, and echoes during phone calls.
These problems were fixed in subsequent releases.