The small business Windows server suite from Microsoft. Designed to integrate with Office 365 and Internet backup such as Windows Azure, Windows Server 2012 R2 Essentials supports up to 25 users and optionally includes Exchange Server for inhouse mail management. It also supports Microsoft's Hyper-V virtualization software. Microsoft's most basic server offering, Windows Server 2012 R2 Foundation runs on a non-virtual server for up to 15 users (see Windows Server 2012). See Windows Azure and Hyper-V. Windows Server Essentials began as BackOffice Small Business Server for Windows NT Server in 1997. In 2001, it was renamed Windows Small Business Server supporting Windows 2000. In 2012, it was renamed Windows Server Essentials.