A Virtual Private Server (VPS) is a method to divide a physical server in several virtual servers, hence each VPS works independently. Each virtual server is able to work under its own operating system and is able to be restarted independently, obtaining then potency, privacy and the security provided by a dedicated server.
Being an environment dedicated, each Virtual Server possesses its exclusive memory space, storage on individual disk, its own management of the operating system ( processes, system permissions, users, programmed tasks and other characteristics).
You will have root access or administrator to your virtual server, which allows installing and full software management, as Data bases, Management Systems, Web servers or E-mail server; you will obtain full control over your server.