Mac OS X is a line of graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike the earlier Macintosh operating system, Mac OS X is a Unix-based operating system built on technology developed at NeXT from the second half of the 1980s until early 1997, when Apple purchased the company. The first version released was Mac OS X Server 1.0 in 1999, which retained the earlier Mac operating system's "platinum" appearance and even resembled OPENSTEP in places. The desktop-oriented version, Mac OS X v10.0, followed in March 2001 sporting the new Aqua user interface. 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, Apple calls Mac OS X v10.5 "Leopard," while its previous release was called "Tiger." 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 specialized versions of OS X for use on three of its consumer devices, the Apple TV, the iPhone and the iPod touch. The iPhone and the iPod touch versions of Mac OS are called iPhone OS. These variants of OS X only contain what is needed for their particular devices.