Microsoft Server 2008 R2

Windows Server 2008 R2
 is a server operating system produced by Microsoft. It was released to manufacturing on July 22, 2009 and launched on October 22, 2009. It is built onWindows NT 6.1, the same core operating system used with the client-oriented Windows 7. It is the first 64-bit-only operating system release from Microsoft.

There are seven editions: Foundation, Standard, Enterprise, Datacenter, Web, HPC Server and Itanium.