A computer that is attached to a network; sometimes called a host.
http://en.wikipedia.org/wiki/Virtual_private_serverThere are two kinds of virtualizations: software based and hardware based. In a software based virtualization environment, the virtual machines share the same kernel and actually require the main node's resources. This kind of virtualization normally has many benefits in a web hosting environment because of quota incrementing and decrementing in real time with no need to restart the node. The main examples are Xen,Virtuozzo, HyperVM, Vserver, and OpenVZ which is the core kernel of both Virtuozzo and HyperVM.