Windows 2000 was released by Microsoft February 17th, 2000 as the successor to Windows NT. It was used for desktop, notebooks and servers. It was initially released in four versions: Professional, Server, Advanced Server, and Datacenter Server. It is the final release to display the Windows NT designation.
Originally called NT 5.0, it was changed to Windows 2000 on Oct. 27th, 1998, and was the first version without a code name. The beta was released in Sept., 1997, ending with Beta 3 on April 29th, 1999. It also introduced Active Directory, Microsoft’s proprietary directory service architecture, which replaced NT’s earlier model. It was summarily dissed by Novell, which was the leader in network directory services at the time. It was also originally intended to replace both NT and Windows 98, but that changed later. New features included NTFS 3.0, the Microsoft Management Console, Automated System Recovery, UDF support, and the Encrypting File System. Windows File Protection and the System File Checker utility were also introduced. Still used in production today, Microsoft has scheduled support to terminate on July 13th, 2010.