VPS hosting is like you are living in an apartment complex. It means that other people are living in the same building, but you have your own secure apartment. You will get more room and restrictions will be fewer as compared to living in a dorm. It also means that if your neighbour is misbehaving, it is the problem of owner of building, not yours.
In answering this question, maybe it’s better to examine how VPS hosting fits in to the overall offerings of most hosting companies. Shared hosting is just that – your site is hosted on a machine with a bunch of other sites, and each of you share the same resources, including RAM, disk space, and CPU.  Your site uses what it needs if it’s available, and if it’s not – well, that’s the limitation of shared hosting. Likewise, a dedicated server is also self-explanatory –  your site is the only one hosted on server, and you have all the aforementioned resources available at your beck and call. Dedicated hosting is therefore  for those large sites with big databases and lots of traffic, whereas the limitations of shared hosting’s usually prevent it from housing that kind of site. Dedicated servers are also relatively expensive, while one can get a shared hosting plan for under $10 per month.
As you can see, a VPS can be the perfect middle ground for many – enough flexibility and resources for those who need more access or control than on a shared server but without the cost of a dedicated server. If you need root access, you can’t get that on a shared server, but you can get it on a VPS. If your site experiences unpredictable swings memory usage, and your host provides it, then the presence of burstable memory will be attractive. And, if you’re a fan of customization, then the fact that you can customize server-level software such as PHP, MySQL, and Apache will perk your interest.  In short, choosing a VPS will allow you to have many of the same characteristics of a dedicated server but in a more affordable and manageable package.