I phone - IOS

It is the operating system that powers many of the company's mobile devices, including the iPhone, and is the basis for three other operating systems made by Apple: iPadOS, tvOS, and watchOS.[9] iOS formerly also powered iPads until iPadOS was introduced in 2019, and the iPod Touch line of devices until its discontinuation.[10] iOS is the world's second most widely installed mobile operating system, after Android. As of December 2023, Apple's App Store contains more than 3.8 million iOS mobile apps.[11]