iPadOS is a mobile operating system created and developed by Apple Inc. for its iPad line of tablet computers. The successor of iOS 12 on iPad, it was announced at the company's 2019 Worldwide Developers Conference (WWDC), as a derivation from iOS but with a greater emphasis on multitasking. It was released in September 2019.

The first iPad was released in 2010 and ran iPhone OS 3.2, which added support for the larger device to the operating system, previously only used on the iPhone and iPod Touch. This shared operating system was rebranded as "iOS" with the release of iOS 4.

The operating system initially had rough feature parity running on the iPhone, iPod Touch, and iPad, with variations in user interface depending on screen size, and minor differences in the selection of apps included. However, over time, the variant of iOS for the iPad incorporated a growing set of differentiating features, such as picture-in-picture, the ability to display multiple running apps simultaneously (both introduced with iOS 9 in 2015), drag and drop, and a dock that more closely resembled the one in macOS than the one on the iPhone (added in 2017 with iOS 11). Standard iPad apps were increasingly designed to support the optional use of a keyboard.

To emphasize the different feature set available on the iPad, and to signal their intention to develop the platforms in divergent directions, at WWDC 2019 Apple announced that the variant of iOS that runs on the iPad would be rebranded as "iPadOS". The new naming strategy began with iPadOS 13.1, in 2019.

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