Adware/Spyware
These are advertising tools that without the proper protection such as a firewall (which is built into Windows Xp SP2 or one may be included in your Anti-virus software ) pop out of nowhere when you visit web sites, becoming a nuisance by distracting you from the information you may be looking for. The worst of these ad-ware packets off load a small program that sends information about you over the internet. This can be in the form of a “key-logger” which captures all keys pressed on your keyboard that is sent as a file when a certain condition is reached. Another form still turns your computer into a zombie which can be controlled from outside your house by a hacker millions of miles away who browses, gets all the information he needs as you go on your coffee break. They can even leave you with a virus (not the cold type, but a malicious program that causes your computer to crash or send innumerable e-mail that overloads other computers turning them into lean mean e-mail machines sending out garbage overloading internet servers and gateways.