Virtual private server (VPS) is a term used by Internet hosting services to refer to a virtual machine. The term is used for emphasizing that the virtual machine, although running in software on the same physical computer as other customers' virtual machines, is functionally equivalent to a separate physical computer, is dedicated to the individual customer's needs, has the privacy of a separate physical computer, and can be configured to run as a server computer (i.e. to run server software). The term Virtual Dedicated Server or VDS is used less often for the same concept, however it may indicate that the server does not use burst/shared ram through multiple machines, as well as individual CPU cores.
In addition to reducing hardware and power expenditures, virtualisation allows businesses to run their legacy applications on older versions of an operating system on the same server as newer applications.
Each virtual server can run its own full-fledged operating system and can be independently rebooted.
The practice of partitioning a single server so that it appears as multiple servers has long been common practice on mainframe computers and mid-range computers such as the IBM AS/400. It has become more prevalent with the development of virtualization software and technologies for microcomputers.