Virtual Private Servers (VPS) allows you to share server costs with other users and give you full control over your own applications. Means share the hardware of a host server, means sharing RAM, CPU, Hard Disk, Network, each VPS can either share hardware resources, or have gauranteed access to limited RAM, a disk space limit and an effective CPU.
In a VPS, your account not hosted in individual directories, but on individual hard disks, means server with multiple hard disks and each one of this has its own system of folder and directories, a single hard disk also divide in many parts using hard disk partition and all partition of disk has unique operating system.

What you get in VPS?
You get full control on server in VPS. You get the root access of the server, if you have knowledge of system administering a server remotely, it's great thing for you.

The advantage of VPS, you get very low cost of dedicated server, full control, you can also get the full managed server from some host.