Mac OS X

Mac OS X (pronounced /mæk oʊ ɛs tɛn/)[3] is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems. It is the successor to Mac OS 9, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 1984. Mac OS X, whose "X" represents the Roman numeral for "10" and is a prominent part of its brand identity, is a Unix-based operating system,[4] built on technologies developed at NeXT between the second half of the 1980s and Apple's purchase of the company in early 1996. Its sixth and most recent version, Mac OS X v10.5 is certified UNIX 03 while running on Intel processors.[5]

The first version released was Mac OS X Server 1.0 in 1999, and a desktop-oriented version, Mac OS X version 10.0 followed on March 24, 2001. Releases of Mac OS X are named after big cats; for example, Mac OS X v10.5 is usually referred to by Apple and users as "Leopard". The server edition, Mac OS X Server, is architecturally identical to its desktop counterpart, and includes tools to facilitate management of workgroups of Mac OS X machines, and to provide access to network services. These tools include a mail transfer agent, a Samba server, an LDAP server, a domain name server, and others. It is pre-loaded on Apple's Xserve server hardware, but can be run on most of Apple's computer models.

Apple also produces specialized versions of Mac OS X for use on three of its consumer devices; the iPhone OS for the iPhone and iPod Touch,[6] and an unnamed version for the Apple TV.[7]
History
Mac OS X is based upon the Mach kernel.[8] Certain parts from FreeBSD's and NetBSD's implementation of Unix were incorporated in Nextstep, the core of Mac OS X. Nextstep was the object-oriented operating system developed by Steve Jobs' company NeXT after he left Apple in 1985.[9] While Jobs was away from Apple, Apple tried to create a "next-generation" OS through the Taligent, Copland and Gershwin projects, with little success.[10]

Eventually, NeXT's OS—then called OPENSTEP—was selected to be the basis for Apple's next OS, and Apple purchased NeXT outright.[11] Steve Jobs returned to Apple as interim CEO, and later became CEO again, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals. The project was first known as Rhapsody and was later renamed to Mac OS X.[12]

Mac OS X Server 1.x, was incompatible with software designed for the original Mac OS and had no support for Apple's own IEEE 1394 interface (FireWire). Mac OS X 10.x included more backward compatibility and functionality by including the Carbon API as well as FireWire support. As the operating system evolved, it moved away from the legacy Mac OS to an emphasis on new "digital lifestyle" applications such as the iLife suite, enhanced business applications (iWork), and integrated home entertainment (the Front Row media center).[13] Each version also included modifications to the general interface, such as the brushed metal appearance added in version 10.3, the non-pinstriped titlebar appearance in version 10.4, and in 10.5 the removal of the previous brushed metal styles in favor of the "Unified" gradient window style.[14][15]