A virtual private server is the process of virtually partitioning a physical server into multiple virtual servers so that each virtual partition runs its own operating system and the ability to run all application and software supported by that particular OS. In other words, the actual hardware server is partitioned into numerous isolated environments.
Sitting somewhere between shared and dedicated hosting, it offers the hosting customers the control and security of dedicated hosting with the affordability of shared hosting.
Virtual private server hosting reduces to eliminate to a considerable extent certain major limitations of shared hosting. Websites do not have to share applications, resources and environment with a large number of other users in the same directory.
This is a very critical characteristic of VPS hosting as a website remains completely isolated from what other websites are doing on the same server. Your website as such is likely to remain unaffected in an event of other websites running additional traffic or some bad script.