Worldwide Developers Conference in the context of "Apple Vision Pro"

macOS (previously OS X and originally Mac OS X) is a proprietary Unix-based operating system, derived from OPENSTEP for Mach and FreeBSD, which has been marketed and developed by Apple since 2001. It is the current operating system for Apple's Mac computers. Within the market of desktop and laptop computers, it is the second most widely used desktop OS, after Microsoft Windows and ahead of all Linux distributions, including ChromeOS and SteamOS. As of 2025, the most recent release of macOS is macOS 26 Tahoe, the 22nd major version of macOS.

Mac OS X succeeded the classic Mac OS, the primary Macintosh operating system from 1984 to 2001. Its underlying architecture came from NeXT's NeXTSTEP, as a result of Apple's acquisition of NeXT, which also brought Steve Jobs back to Apple. The first desktop version, Mac OS X 10.0, was released on March 24, 2001. Mac OS X Leopard and all later versions of macOS, other than OS X Lion, are UNIX 03 certified. Each of Apple's other contemporary operating systems, including iOS, iPadOS, watchOS, tvOS, audioOS and visionOS, are derivatives of macOS. Throughout its history, macOS has supported three major processor architectures: the initial version supported PowerPC-based Macs only, with support for Intel-based Macs beginning with OS X Tiger 10.4.4 and support for ARM-based Apple silicon Macs beginning with macOS Big Sur. Support for PowerPC-based Macs was dropped with OS X Snow Leopard, and it was announced at the 2025 Worldwide Developers Conference that macOS Tahoe will be the last to support Intel-based Macs.

iOS 26 is the nineteenth and the current major release of Apple's iOS operating system for the iPhone. It was announced on June 9, 2025, at the 2025 Worldwide Developers Conference (WWDC), and released on September 15, 2025.

The successor to iOS 18, its version number was brought forward to 26 as Apple changed its version numbering convention for consistency across its operating systems.

iOS 12 is the twelfth major release of the iOS mobile operating system developed by Apple. Aesthetically similar to its predecessor, iOS 11, it focuses more on performance than on new features, quality improvements and security updates. Announced at the company's Worldwide Developers Conference on June 4, 2018, iOS 12 was released to the public on September 17, 2018. It was succeeded for the iPhone and iPod Touch by iOS 13 on September 19, 2019, and for the iPad by iPadOS 13 on September 24, 2019. Security updates for iOS 12 continued for four years after the releases of iOS 13 and iPadOS 13 for devices unable to run the newer versions. The last update, 12.5.7, was released on January 23, 2023.

macOS Tahoe (version 26) is the twenty-second and current major release of Apple's macOS operating system. The successor to macOS Sequoia (macOS 15), it was announced at WWDC 2025 on June 9, 2025, and its first developer beta was released the same day. It was released on September 15, 2025.

Tahoe is the final version of macOS that supports Macs with Intel processors; the 2020 iMac, the 2019 16-inch MacBook Pro, the 2020 4-port 13-inch MacBook Pro, and the 2019 Mac Pro models are supported. Future versions will work only on Macs with Apple silicon systems on a chip (SoCs). It is the first version of macOS since Mac OS X Snow Leopard that cannot be upgraded from an older version via the Mac App Store; upgrading it is exclusively available through the System Settings software update preference pane, as is the case with iOS.

macOS Big Sur (version 11) is the seventeenth major release of macOS, Apple's operating system for Macintosh computers. It was announced at Apple's Worldwide Developers Conference (WWDC) on June 22, 2020, and was released to the public on November 12, 2020.

Big Sur is the successor to macOS Catalina (macOS 10.15). The release of Big Sur was the first time the major version number of the operating system had been incremented since the Mac OS X Public Beta in 2000. After sixteen distinct versions of macOS 10 ("Mac OS X"), macOS Big Sur was presented as version 11 in 2020, and four subsequent versions incremented the major version number, similarly to previous versions of Apple's other OSes.

Mac OS X Snow Leopard (version 10.6) (also referred to as OS X Snow Leopard) is the seventh major release of macOS, Apple's desktop and server operating system for Macintosh computers.

Snow Leopard was publicly unveiled on June 8, 2009, at Apple’s Worldwide Developers Conference. On August 28, 2009, it was released worldwide, and was made available for purchase from Apple's website and retail stores at the price of $29 USD for a single-user license. As a result of its low price, initial sales of Snow Leopard were significantly higher than its predecessors, which had prices starting at $129 USD. The release of Snow Leopard came nearly two years after the launch of Mac OS X Leopard, the second longest time span between successive Mac OS X releases (the time span between Tiger and Leopard was the longest).