Spyware detection programs are used to monitor, scan, and remove spyware from your computer.

The main action of spyware is to gain as much information about you as possible. Usually this information is used for advertising purposes, but there are certain types of spyware that exists to record personal information about you, such as credit card numbers, or find vulnerabilities in your system that can be used to hack into your computer.

Spyware detections programs use two different methods to detect spyware, one for known spyware and the other for suspected new spyware.

Detection of Known Spyware

The first way that spyware detection programs work is to look for code matches between the spyware located on your computer and the spyware dictionary located within the detection program. When a match is made, the detection program will inform you and remove the spyware from your computer.

Detection of Spyware by Heuristic Analysis

The second way in which spyware detection programs work is to monitor the computer for behavior that might suggest that spyware is present. Usually it is not always obvious that spyware is located on a computer system, and instead it will lurk in the background, gathering as much information as possible.

For example, undetected spyware behavior can include changing your Internet Explorer homepage, disabling files necessary for programs to work, or frequent popups on the desktop. Some users that are knowledgeable about their computer will notice that it slows down considerably when spyware is present.

For recommendations on sypware detection and removal software, read What is free spyware removal software?.