Mac OS X Tiger in the context of "MacOS"

Mac OS X Panther (version 10.3) is the fourth major release of macOS, Apple's desktop and server operating system. It followed Mac OS X Jaguar and preceded Mac OS X Tiger. It was released on October 24, 2003, with the retail price of US$129 for a single user and US$199 for a five user, family license.

The main features of Panther included a refined Aqua theme, Exposé, Fast user switching, and a new Finder. Panther also included Safari as its default browser, as a change from Internet Explorer in Jaguar.

Mac OS X Leopard (version 10.5) is the sixth major release of macOS, Apple's desktop and server operating system for Macintosh computers. Leopard was released on October 26, 2007, as the successor of Mac OS X Tiger, and is available in two editions: a desktop version suitable for personal computers, and a server version, Mac OS X Server. It retailed for $129 for the desktop version and $499 for Server. Leopard was superseded by Mac OS X Snow Leopard (version 10.6) in 2009. Mac OS X Leopard is the last version of macOS that supports the PowerPC architecture as its successor, Mac OS X Snow Leopard, functions solely on Intel based Macs. It is also the first version of Mac OS X not to support the G3 family of PowerPC processors.

According to Apple, Leopard contains over 300 changes and enhancements compared to its predecessor, Mac OS X Tiger, covering core operating system components as well as included applications and developer tools. Leopard introduces a significantly revised desktop, with a redesigned Dock, Stacks, a semitransparent menu bar, and an updated Finder that incorporates the Cover Flow visual navigation interface first seen in iTunes. Other notable features include support for writing 64-bit graphical user interface applications, an automated backup utility called Time Machine, support for Spotlight searches across multiple machines, and the inclusion of Front Row and Photo Booth, which were previously included with only some Mac models.

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).