A firewall is the first line of defense to keeping your computer clean. In the simplest of terms - it keeps bad stuff out. A firewall can be a built in to a piece of hardware (such as a router) or a software program, but you must have one and it must be on all of the time.

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Without this, you needlessly expose yourself to hijacker attacks and viruses. It is far easier to keep your machine clean, blocking them right from the start,than to try and fix the damage once it's already done. Think of it as a barrier. It looks for certain types of files, or types of requests from both inbound and outbound information on your computer. It then accepts or rejects those requests based on the "rules" it's been told to watch for. It can't recognize "disguised" requests or things it's not been told to monitor, and that's why you still need virus scanners, spyware programs, etc. But without the firewall not only would more bad stuff make it through, you'd be completely open to hackers as well.

Hardware incorporating a firewall is incredibly secure. Routers (Such as those from Linksys) which are designed for high speed cable/DSL connections often have a firewall and ethernet card built in. They provide an inexpensive way to protect your system. For the basic user, having a router with built in firewall is probably sufficient. You may choose to add a program on top of this to offer additional protection. I personally, as do quite a few people I know, use only a firewalled router. However, depending on the types of surfing and downloads you do (especially if you do P2P sharing) you may want to add the extra layer of protection. Typically, adding a software program on top of the hardware will not cause conflicts.

If however, you do not have such a router, or you want a second layer on top of one, Windows offers a basic firewall as a part of XP and Vista - known as Windows Firewall. If you have no other options, I certainly would use this as you must have something, but there are other programs out there which are freely available. You are certainly not limited to the one that may have come on your machine. There are many FREE programs which are quite good. Visit www.filehippo.com and browse the "Firewalls and Security" section. Here you can find several of the better ones and it won't cost you a thing. Comodo Firewall is one that has been highly recommended by several of my friends. I'm told it's easy to configure and works great.

Whichever method(s) you choose, be sure you have a firewall and it is constantly on. Router firewalls will require periodic updates to firmware, just as programs require updates to the software from time to time. Checking to be sure you are up to date should be a part of your regular maintenance. A couple of times a year is probably sufficient to check for firmware updates. For software, most programs offer an automatic update feature, or at a minimum have an option on the main menu to check manually for them.

All this might lead you to think multiple firewall software programs on your pc would be beneficial. This is actually not the case! While hardware and a single software firewall generally play fairly well together, when you install multiple software firewalls, they tend to "fight" over who has control of different ports, aspects, etc. and you may end up with programs not functioning properly, difficulty accessing the internet and/or downloading information plus an annoying number of errors popping up. If you choose the software route, make sure you select only one program. If you end up not liking it you can always remove it and replace it with another one. Also keep in mind, Windows enables the Windows Firewall automatically. If you choose another software program, you should disable the Windows Firewall by going to Control Panel/Windows Firewall and turning it Off.

A word of caution - for those of you running on only a firewalled router (like I do) - if you do any travel where you take your laptop with you, be sure to re-enable the Windows Firewall, or have a backup software program installed. You never know what level of protection the service you may use to access the internet will have(if it even has one) when you're away from home.

So that's firewalls in a nutshell. Nothing to deep or difficult. In today's world, it's more important than ever to use one. With so many computers connected 24/7 the probability of an attack on your system is high. Without this critical element of protection, you will likely find yourself trying to recover from some very bad things. In the worst case scenario, you can lose everything and be forced to wipe your hard drive clean. I'm amazed when I hear of someone running without a firewall.

Want to test your firewall and see how secure you are? Click here to visit Audit My PC for a free test of your firewall. They also offer some other good tools you might like to check out too.