“Firewall” is a term that most computer users have heard at some point. Many are still unaware of exactly what a firewall does, however. Most widely used by private computer networks, firewalls serve a vital role in protecting computers.

A firewall works as a security guard for your computer by accepting or turning away information. Firewalls help to establish a computer’s (or a computer network’s) levels of trust. In a private computer network, such as the kind maintained by large companies, firewalls help keep outside information from permeating the security of the network.

Put simply, the main function of a firewall is to keep online threats away from the PC or network of computers. Such threats can include viruses, worms, spyware, and other harmful programs. A firewall works as a filter to protect computers from hackers who seek to wreak havoc on any computer system they are able to breach.

The types of malicious programs that firewalls block vary greatly. Here are some of the problems an unprotected computer can experience if it becomes infected:

* A hijacked system. Some types of malware can actually gain complete control of your computer through remote access. Signs that your computer has been hijacked include a change in your homepage or an alteration in your desktop icons.

* A slow system. If you notice a considerable change in your computer’s performance, you may be infected with a virus or spyware. Sometimes such programs clog up so much of you bandwidth that the computer becomes unusable.

* Incessant pop-ups. Pop-up advertisements appear to be simple annoyances in small numbers. However, a bombardment of pop-ups can cause a computer to become paralyzed by the number of advertisements.

* A stolen identity. Some types of malware has the ability to slip into your system through a backdoor. These programs can then come and go as they please, logging personal information and sending it back to the hacker. Sometimes such malware can include a keylogger, which records everything you type, including usernames and passwords to secure websites.

There are several types of firewalls including:

* Application-layers

* Proxy

* Packet filter

* Stateful inspection

Regardless of the type of firewall, most can be customized to keep users away from certain types of content or specific websites; This kind of customization is often utilized by large companies that seek to block employees from visiting certain types of websites. Firewalls are customized by blocking things such as:

* Specific IP addresses. All sites are assigned a numerical IP address.

* Individual domain names. A company can create a list of domain names for which they would like to block their employees from visiting.

* Specifically identified words or groups of words. Like the domain names, a company can identify words. This way the firewall can block websites associated with such words.

While firewall protection tends to be associated with larger networks of computers, it is smart for PC users to also set up firewalls. You are just as vulnerable at home as you are in the office. The Internet is a virtual Wild West, full of hackers looking to cause problems for your computer and steal your personal information. Don’t overlook the necessity of a firewall for the computer that you and your family depend on. With all of the important information that is transferred and accessed through it, a firewall is certainly a necessity.