Firewall

From SuperbHosting.net Support Wiki

In order to help you better understand what a firewall is, consider its original meaning. A firewall originally stood for a wall or partition that has been built with fireproof material in order to prevent the spread of fire from one place to another. The meaning of firewall with respect to computers is very similar to this. The firewall in your computer is a device which is created and designed to permit, deny, encrypt, or proxy all computer traffic between different security domains based upon a set of rules, regulations and specific criteria.

It is the firewall's most basic task, to simply regulate the flow of traffic between computer networks and monitor and manage it at different trust levels. So if you are ever nervous about the quality or content of traffic that is entering your computer, you can feel safe knowing that you have taken a preventative measure with a firewall.