A virtual private server (VPS), also called a virtual dedicated server (VDS), is a virtual server that appears to the user as a dedicated server, but that is actually installed on a computer serving multiple websites. A single computer can have several VPSs, each one with its own operating system (OS) that runs the hosting software for a particular user.
Virtual private servers connect shared Web hosting services and dedicated hosting services by filling the gap between them. Because virtual dedicated servers can have their own copy of the operating system, VPS provides the user with super-user privileges in the operating system. VPS enables the user to install any kind of software that is capable of running on that operating system.
The main reason that someone signs up for a VPS is that they need a server through which to run their site. When you adopt one, you should notice that your site is performing better than it was on a shared account (because of the guaranteed allotment of resources). Also, the full root access gives you better control. You are able to install and get rid of whatever programs you want.
Partitioning a single server to appear as multiple servers has been increasingly common on microcomputers since the launch of VMware ESX Server in 2001. The physical server typically runs a hypervisor which is tasked with creating, releasing, and managing the resources of "guest" operating systems, or virtual machines. These guest operating systems are allocated a share of resources of the physical server, typically in a manner in which the guest is not aware of any other physical resources save for those allocated to it by the hypervisor. As a VPS runs its own copy of its operating system, customers have superuser-level access to that operating system instance, and can install almost any software that runs on the OS; however, due to the number of virtualization clients typically running on a single machine, a VPS generally has limited processor time, RAM, and disk space.