OS X is the newest of Apples Mac OS line of operating systems. Although, under its original name of Mac OS X, it was officially designated as simply "version 10" of the Mac OS, "version 9" had a completely different codebase as well as dramatic changes in user interface. Mac OS had been Apple's primary operating system since 1984, and the family was backward compatible, so OS X could virtualize Mac OS 9 until version 10.5. Unlike its predecessor, OS X is a Unix operating system built on technology that had been developed by NEXT through the second half of the 1980s and up until Apple purchased the company in early 1997. It was first released in 1999 as Mac OS X Server 1.0, with a desktop-oriented version (Mac OS X v10.0) following in March 2001. Since then, six more distinct "client" and "server" editions of Mac OS X were released, thereafter starting with Mac OS X v10.7 Lion, OS X Server is no longer offered as a separate operating system product; instead, the server management tools are available for purchase separately. The most recent version OS X 10.9 Mavericks was first made available on October 22, 2013.
After Apple removed Steve Jobs from management in 1985, he left the company and attempted - with funding from Ross Perot[4] and from his own pockets - to create the "next big thing". The result was NeXT. NeXT hardware was advanced for its time, being the first workstation to include a DSP and a high-capacity optical disc drive, but it had several quirks and design problems and was expensive compared to the rapidly commoditizing workstation market. The hardware was phased out in 1993; however, the company's object-oriented operating system NeXTSTEP had a more lasting legacy.
Until OS X 10.9 Mavericks, all OS X versions were named after big cats, with the exception of Mac OS X Server 1.0 and the original public beta. Just recently Apple announced that all future OS X versions would be named after cities in California.