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. Support for the IA-64 architecture was dropped with this release.

Since this version of Windows Server is based on the NT 6.2 kernel, it's also the first version of Windows Server to drop support for CPUs that lack SSE2, and NX/XD (the client counterpart additionally required PAE support for x86 systems, but the server version is only shipped with an AMD64 kernel, meaning PAE support is not a consideration. Regardless running on a CPU that doesn't support SSE2 or NX will bug check the system with code 0x5D). This is the last version of Windows Server to support processors without the CMPXCHG16b, PrefetchW and LAHF/SAHF instructions. It is the first server release of Windows to drop the traditional Service Pack mechanism in favor of releasing updates on a continual basis in smaller chunks.

It is also the first release of Windows Server to have an Essentials edition which included all features and functionalities of the former Home Server and Small Business Server product lines.

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