Modern server computers are so powerful nowadays that they generally have a large degree of spare computing power.

Rather than buy additional servers, it is possible to create several virtual servers on one physical server. Each virtual server is allocated a slice of the available computing power.

As well as providing efficiency savings by reducing the need to buy more hardware, virtualisation also enables one physical machine to run several different operating systems. Therefore a Windows server and a Linux server can run on the same machiine.

Special virtualisation software supplied by companies such as VMWare is required to run several virtual computers on one physical machine.