Windows Server 2012

Windows Server 2012 is the server counterpart of Windows 8. It replaces Windows Server 2008 R2 and was replaced by Windows Server 2012 R2. It reached RTM on 1 August 2012 and was released on 4 September of that year. Support for the IA-64 architecture was dropped with this release.

This is the first version of Windows Server to drop support for processors without PAE, SSE2 and NX, as running on these processors will cause an  bugcheck upon boot. It is also the last version of Windows Server to support processors without the CMPXCHG16b, PrefetchW and LAHF/SAHF instructions.

Notably, it is the first release of Windows Server to include an Essentials edition, which contains all features and functionalities of the former Home Server and Small Business Server product lines. It is also the first server release of Windows to drop the traditional Service Pack mechanism in favor of releasing updates in smaller chunks on a continual basis.

Windows Server 2012 drops the ability to upgrade from versions prior to Windows Server 2008 R2.

Editions
There are four major editions of Windows Server 2012:

This release drops both the Enterprise and Web Server SKUs, first introduced in Windows NT 4.0 and Windows Server 2003 respectively.
 * Windows Server 2012 Foundation
 * Windows Server 2012 Essentials
 * Windows Server 2012 Standard
 * Windows Server 2012 Datacenter