A list of great firewalls.

[Elektrisk]

Simply put, "A firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications."

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So, regardless of whether or not you realise WHAT a firewall does, at least realise that it's VITAL for your system's security. I used to think, "Ugh! Firewalls are so annoying; screw them!" And while they can be annoying, if you use a friendly one such as Online Armor, then this problem can easily be avoided.

Online Armor
Outpost
ZoneAlarm
Comodo

I'd personally recommend Online Armor. If you like the free version, you should get the Professional edition. It's extremely good. However, I've heard good things about ZoneAlarm and Comodo as well. I've also heard that Sunbelt is a good alternative, but it appears there isn't a non-trial free edition. Be aware that Windows Firewall is NOT adequate to be secure if you are running XP or Vista! If you are running Windows 7, then it's fine, as it has been drastically improved. But, if you are running XP or Vista, do yourself a favor and download one of the aforementioned firewalls

Enjoy!