iOS

iOS (formerly iPhone OS) is a mobile operating system developed by Apple Inc. exclusively for its smartphones. It was unveiled in January 2007 for the first-generation iPhone, launched in June 2007.

It is the operating system that powers many of the company's mobile devices, including the iPhone. It was also used on iPads (introduced: January 2010; availability: April 2010) until iPadOS was introduced in 2019, and on the iPod Touch devices, which were discontinued in mid-2022. It is the world's second-most widely installed mobile operating system, after Android. It is the basis for three other operating systems made by Apple: iPadOS, tvOS, and watchOS.

As of December 2023, Apple's App Store contains more than 3.8 million iOS applications. These mobile apps have collectively been downloaded more than 130 billion times.

iOS is based on macOS. Like macOS, it includes components of the Mach microkernel and FreeBSD. It is a Unix-like operating system. Although some parts of iOS are open source under the Apple Public Source License and other licenses, iOS is proprietary software.

Major versions of iOS are released annually. The current stable version, iOS 17, was released to the public on September 18, 2023.