Spyware is considered a malicious program and is very similar to a Trojan Horse in that you install the product when you install something else. A common way to become a victim of spyware is to download certain peer-to-peer file-swapping products as well as some freeware like games, music or applications. There are even malicious people who actually hide spyware in “anti-spyware” programs. This way people install the program, thinking it will remove existing spyware from their computer but, in fact, you actually install spyware.

In addition to privacy issues (some spyware can transmit every bit of information you enter on the Web back to a third party) . It could also monitor your surfing habits, install unwanted toolbars and change your browser settings and homepage. Some spyware can flood your system with so many pop-ups that it uses large portions of hard drive space and system resources to the point of notably slowing it down, or worse, making your system unstable and unusable.