What is Server Virtualisation?

Server virtualisation abstracts server software from hardware on a guest/host basis, enabling multiple virtual servers to run on a physical device.

Server virtualisation definition

Server virtualisation is a software architecture that allows more than one server operating system to run as a guest on a given physical server host. With the server software abstracted away from the physical machine in this way, the server becomes a "virtual machine," detached from the physical plane – though the server "thinks" it is running exclusively on the compute and memory resources. It’s actually running on a virtual imitation of the server hardware.