Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, Mac OS X has been included with all new Macintosh computer systems. It is 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.
Mac OS X consists of a Mach/BSD-based kernel, userland primarily based on FreeBSD, and additional frameworks (written in C, C++ and Objective-C) providing user interface and application-level services.
