iOS

iOS, formerly iPhone OS is a proprietary mobile operating system developed by Apple Inc. primarily for its iPhone product line. The iPhone was first unveiled in January 2007. The device introduced numerous design concepts that have been adopted by modern smartphone platform, such as the use of multi-touch gestures for navigation, eschewing physical controls such as physical keyboards in favor of those rendered by the operating system itself on its touchscreen including the keyboard, and the use of skeumorphism-making features and controls withing the use interface resemble real-world objects and concepts in order to improve their usability. 

In 2008, Apple introduced the App Store, a centralized storefront for purchasing new software for iPhone devices. iOS can also integrate with Apple's desktop music program iTunes to sync media to a personal computer. The dependency on a PC was removed with the introduction of iCloud on later versions of iOS, which provides synchronization of user data via internet servers between multiple devices. The iPhone line's early dominance was credited with reshaping the smartphone industry, and helping make Apple one of the world's most valuable publicly traded companies by 2011. However, the iPhone and iOS have generally been in second place in worldwide market share.

iOS is a mobile operating system created and developed by Apple Inc. and distributed exclusively for Apple hardware. It is the operating system that presently powers many of the company's mobile devices, including the iPhone, iPad, and iPod touch. It is the second most popular mobile operating system in the world by sales, after Android. iPad tablets are also the second most popular, by sales, against Android since 2013, when Android tablet sales increased by 127%.

Originally unveiled in 2007, for the iPhone, it has been extended to support other Apple devices such as the iPod Touch (September 2007)  and the iPad (January 2010). As of June 2016, Apple's App Store contained more than 2 million iOS applications, 725,000 of which are native for iPads. Theses mobile apps have collectively been downloaded more than 130 billion times.

The iOS user interface is based on the concept of direct manipulation, using multi-touch gestures. Interface control elements consist of sliders, switches, and buttons. Interaction with the OS includes gestures such as swipe, tap, pinch, and reverse pinch, all of which have specific definitions within the context of the iOS operating system and its multi-touch interface. International accelerometers are used by some applications to respond to shaking the device, one common result is the undo command, or rotating in three dimensions, one common result is switching between portrait and landscape mode.  

iOS shared with OS X some frameworks such as Core Foundation and Foundation Kit, however, its UI tookkit is Cocoa Touch rather than OS X's Cocoa, so that it provides the UIKit framework rather than the Appkit framework. Therefore, it is notcompatible with OS X for applications. Also, while iOS shared the Darwin foundation with OS X, Unix-like shell access is not available for users and restricted for apps, preventing iOS from being fully Unix-compatible.

Major versions of iOS are released annually. The current release, iOS 9.3.5, was released on August 23, 2016. In iOS, there are four abstraction players: the Core OS layer, the Core Services layer, the Media layer, and the Cocoa Touch layer. The current version of the operating system, iOS 9, dedicates around 1.3 GB of the device's flash memory for iOS itself. It runs on the iPhone 4S and later, iPad 2 and later, iPad Pro, all models of the iPad mini, and the 5th-generations iPod Touch and later.