Personal firewall
A personal firewall looks after the security of your internet connection. It blocks any malicious attempts by hackers to connect to your PC.
A firewall also lets you decide which programs are allowed to connect to the web. If a program tries to connect to the internet when you haven't previously given permission, your computer will display a warning. You can then decide whether to allow or block the connection. This helps guard against viruses, adware and spyware.
Windows XP comes with a firewall built in, and a number of free and reasonably priced personal firewall programs are available.
