Mac OS X version 10.2 "Jaguar" is the third major release of Mac OS X, Apple's desktop and server operating system. It superseded Mac OS X v10.1 code name Puma and preceded Mac OS X Panther (version 10.3). The operating system was initially available on 23 August 2002 either for single-computer installations, and in a "family pack", which allows five installations on separate computers in one household. The operating system was generally well-received by Macintosh users^[which?] as a large step forward in the areas of stability, general speed enhancements, compatibility with other flavors of Unix and the lineup of both graphical and command line applications available; however, many critics^[who?] still claimed that significant user interface speed issues existed and that the operating system was still a big step up from OS9. Jaguar was the first Mac OS X release to publicly use its code name in marketing and advertisements,^{[citation needed]} a practice that has continued in subsequent releases of the operating system.

OS X ( /oʊ ˌɛs ˈtɛn/), formerly Mac OS X, is a series of Unix-based graphical interface operating systems developed, marketed, and sold by Apple Inc. OS X (officially) runs exclusively on Macintosh computers and has been pre-loaded on all Macs since 2002.

OS X, whose X is the Roman numeral for 10 and is a prominent part of its brand identity, is built on technologies developed at NeXT between the second half of the 1980s and Apple's purchase of the company in late 1996. It was the successor to Mac OS 9, released in 1999, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 1984.

OS X is a UNIX-like operating system that originally ran on PowerPC-based Macs. In 2006, the first Intel Macs had a specialized version of Mac OS X v10.4 "Tiger". in 2007, Mac OS X 10.5 "Leopard", was the first to have UNIX 03 certification and run on both PowerPC and Intel Macs with the use of Universal Binaries. Mac OS X 10.6 "Snow Leopard" was the first version of OS X to drop support for PowerPC Macs and run solely on Intel's x86-based processors. Mac OS X 10.7 "Lion" was the first version of OS X to drop support for 32-bit processors and run exclusively on 64-bit CPUs.