|1999-12-15 (RTM), 2000-02-17 (GA)
|Windows NT 4.0
|Windows XP, Windows Server 2003
Windows 2000 is an NT-based version of Windows released by Microsoft that succeeded Windows NT 4.0, and is the fifth operating system in the Windows NT line. It reached general availability on 17 February 2000 after releasing to manufacturing two months prior on 15 December 1999. It was Microsoft's business operating system until the introduction of Windows XP Professional in 2001.
Windows 2000 introduced NTFS 3.0, Encrypting File System, as well as basic and dynamic disk storage. Support for people with disabilities was improved over Windows NT 4.0 with a number of new assistive technologies, and 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.