Private VPS Parent Hosting is a way to get the benefits of virtualization without sharing a parent server with other companies. This is a robust, flexible, and isolated virtual solution that gives you sole control over a built-to-order parent server and its resources. That means you can add as many VPS environments as the server allows and control them all as you see fit.
Expert Overview:
It comes down to basic reasons: If your business is growing and receiving more traffic, it is time to move to a more controlled setting like VPS.
A VPS doesn’t just have more RAM, disk space, and a  proprietary share of CPU than a shared account. Depending on the provider, some VPS plans offer burstable memory, which is a pool of RAM set aside for extraordinary events. This is the stuff that can help counter the so-called “Digg-effect,” that much-whispered about occurrence that’s the simultaneous hope and fear of everyone who runs a web site. When you have an unexpected high traffic event, burstable memory will call on a pool of reserved, shared memory to satisfy the needs of temporary high traffic. This is not available on shared servers and, while the necessary memory is available on a dedicated server, your site might not get the kind of traffic on a daily basis to justify the expense of a dedicated server. Again, not all VPS plans have burstable memory, so ask your provider if their VPS plans do.

Unlike most shared web hosting plans with unlimited domains, almost all VPS hosting plans include metered bandwidth limits of between 1-5 TB per month. VPS hosting plans have better resource utility panels for administration than available with cPanel where web traffic statistics can be accessed in realtime and the levels of RAM, CPU cores, or bandwidth limits can be adjusted.
You’re paying more, so there SHOULD be a minimum uptime guarantee and better server speed. Look for a host that offers 99.5% at a very minimum, although ideally, I’d rather go with someone who offers 99.9%. Search through some reviews as there are many who have put this to the test. For example, any of WHSR’s many web host reviews include an uptime record as one of our key tests.
If you are familiar with hosting control panels, shell commands, and you have basic server administration and troubleshooting skills, then unmanaged VPS is the way to go. Note that while you purchase self­ managed VPS, you should be capable of managing applications, software, services installed on your VPS. Also, you must know installation/un­installations, resource monitoring, server performance tweaking and troubleshooting of any technical issues.