Windows 2000 is a major release of the Windows NT operating system developed by Microsoft, targeting the server and business markets. It is the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and then to retail on February 17, 2000 for all versions, with Windows 2000 Datacenter Server being released to retail on September 26, 2000.
Windows 2000 introduces NTFS 3.0, Encrypting File System, and basic and dynamic disk storage. Support for people with disabilities is improved over Windows NT 4.0 with a number of new assistive technologies, and Microsoft increased support for different languages and locale information. The Windows 2000 Server family has additional features, most notably the introduction of Active Directory, which in the years following became a widely used directory service in business environments. Although not present in the final release, support for Alpha (which was a 64-bit platform but only distributed as a 32-bit OS) was present in its alpha, beta, and release candidate versions. Its successor, Windows XP, only supports x86, x64 and Itanium processors. Windows 2000 was also the first NT release to drop the "NT" name from its product line.