By John Lenaghan
Shared hosting is a great option for a lot of websites as it brings the cost down considerably. It does have some disadvantages, however. Your site's CPU, disk space and bandwidth can be affected by other sites on the same server.
If your site is relatively small, these resource issues may not be a problem. Another downside to shared hosting is lack of system-level control. You may not have any control over things such as system software and scripts.
While many webmasters don't need to worry about these things, there are some that do. If you fall into that category, you might want to look at a Virtual Private Server (VPS) for your hosting.
A VPS is a single physical server that has been divided into a few "virtual machines" through software running on the server. The server's resources - RAM, disk space, etc. - are still shared, but each VPS gets its own allotment and operated completely independently from the others.
This independence lets you run scripts or software - even install a different operating system - without having any effect on the other virtual servers on the same machine.
One of the biggest advantages of a VPS is the fact that you get "root" level access to your server. This means you can install or delete any software you want, create any accounts you want, set permissions the way you want - effectively all the same things you can do on a dedicated server, only at a lower cost.
A VPS is also more secure than shared hosting. On a shared server, all the websites are running within the same operating system. If the server gets hacked, all the sites will be vulnerable.
With a VPS, because of the way the virtual servers are divided, if one of them gets hacked none of the others are visible to the hacker. They're effectively like different computers.
Virtual Private Servers can be configured in a number of ways so you should be sure that you find out how any particular host has set them up.
In most cases, the server's total resources are divided evenly by the number of VPS's on the machine. ie. If there are 10 virtual servers, the total RAM, disk space, etc. is simply divided by 10 and each VPS gets 10% of the total.
The disadvantages of a VPS are related to the same things as the advantages. Because you have complete control over the system, you can run into problems if you don't know what you're doing.
You can delete the wrong files, set permissions incorrectly, create security vulnerabilities and more if you're not careful.
If you aren't familiar with server administration and don't have time to learn, you should either hire someone to do it for you or find a host who manages the server for you.