OS X Lion, also known as Mac OS X Lion, (version 10.7) is the eighth major release of macOS, Apple's desktop and server operating system for Mac computers.
A preview of OS X 10.7 Lion was publicly shown at the "Back to the Mac" Apple Special Event on October 20, 2010. It brought many developments made in Apple's iOS, such as an easily navigable display of installed applications, to the Mac, and includes support for the Mac App Store, as introduced in Mac OS X 10.6 Snow Leopard version 10.6.6.
On February 24, 2011, the first developer's preview of Lion (11A390) was released to subscribers to the Apple Developer program. Other developer previews were subsequently released, with Lion Preview 4 (11A480b) being released at WWDC 2011.
Lion was released to manufacturing on July 1, 2011, followed by its final release via the Mac App Store on July 20, 2011. Apple reported over one million Lion sales on the first day of its release. , OS X Lion had sold over six million copies worldwide.
Lion is the first version of macOS that did not support 32-bit processors and is also the final release whose development was overseen by Bertrand Serlet, considered to be the "founding father of Mac OS X".
Although originally paid, Apple later allowed free downloads of the OS, especially for customers of older and no longer officially supported Mac computers, starting on June 30, 2021. The same practice was applied to its successor, OS X Mountain Lion.
On June 6, 2011, at the Apple Worldwide Developers Conference, it was announced that the official release for Lion would be in July 2011. The specific release date of July 20 was not confirmed until the day before, July 19, by Apple CFO, Peter Oppenheimer, as part of Apple's 2011 third-quarter earnings announcement.
Apple did not initially announce any physical media distribution for Lion, such as a set of CD-ROMs or a DVD-ROM as used for past releases. Instead, the operating system was said to be available exclusively as a download from the Mac App Store for US$29.99.