iOS

iOS (formerly iPhone OS) is a mobile operating system developed by Apple exclusively for its mobile devices. It was unveiled in January 2007 for the first-generation iPhone, which launched in June 2007. Major versions of iOS are released annually; the current stable version, iOS 18, was released to the public on September 16, 2024.

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. iOS formerly also powered iPads until iPadOS was introduced in 2019, and the iPod Touch line of devices until its discontinuation. 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.

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.