Spy ware is a software program that watches what a user does on his computer. This program sends the information it has gathered on the users activities to a hacker over the internet. The information of the websites a user visits is collected and sent to advertisement agencies. More malicious spy ware can record all the keys that have been typed by the user. This method is used to gain passwords and credit card numbers of the user. Advertisement goals are furthered by Pop-Up advertisement and routing of HTTP requests to advertising sites.

How is your computer infected?
In most cases it is installed by the user.