Windows Server is a brand name for a group of server operating systems released by Microsoft. It includes all Windows operating systems that have "Windows Server" in their names, but not any other Microsoft product. The first Windows server edition to be released with that brand was Windows Server 2003. However, the first server edition of Windows was Windows NT 3.1 Advanced Server, followed by Windows NT 3.5 Server, Windows NT 4.0 Server, and Windows 2000 Server; the latter was the first server edition to feature many things like Active Directory, DNS Server, DHCP Server, Group Policy, and many other popular features used today.
This brand includes the following operating systems:
- Windows Server 2003 (April 2003)
- Windows Server 2003 R2 (December 2005)
- Windows Server 2008 (February 2008)
- Windows Server 2008 R2 (July 2009)
- Windows Server 2012 (August 2012)
- Windows Server 2012 R2 (October 2013)
- Windows Server 2016 (upcoming)
Microsoft has also produced Windows Server Essentials (formerly Windows Small Business Server) and Windows Essential Business Server (discontinued), software bundles which includes a Windows Server operating system and some other Microsoft Servers products.