Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike its predecessors, Mac OS X is a Unix-based operating system built on technology that had been developed at NeXT through the second half of the 1980s until Apple purchased the company in early 1997.
The first version released was Mac OS X Server 1.0 in 1999, and a desktop-oriented version, Mac OS X v10.0 followed in March 2001. Since then, five more distinct "end-user" and "server" versions have been released, most recently Mac OS X v10.5 in October 2007. 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 very similar to its desktop counterpart but usually runs on Apple's line of Macintosh server hardware. It includes workgroup management and administration software tools that provide simplified access to key network services, including a mail transfer agent, a Samba server, an LDAP server, a domain name server, and others. Apple also produces customized versions of OS X for use on three of its consumer devices, the Apple TV, the iPhone and the iPod touch. The modified OS only contains what is needed for that particular device (un-needed drivers and components are removed), though certain sources have reported that simple hacks could install features in the Mac OS to the stripped down version, which could indicate Apple wants to improve upon a common platform on all its hardware devices.
