Malware is software designed to infect a computer without the user’s knowledge and damage the system, cause it to act abnormally, or take control of it. The term is a combination of the words “Malicious” and “Software”.

It is a broad description that includes all software threats which are deliberately created for malicious purposes such as Viruses, Worms, Trojan Horses, Keyloggers and Spyware.

In some cases Malware will not damage your computer, but will turn your system into a “drone” which the software’s creator can then use to distribute other Malware or to conduct illegitimate activities such as spam emailing (ie. “Sobig” or “MyDoom”). The only visible sign of such an infection is reduced system performance.

In other cases, Malware is used as a tool for identity theft. Professional online theft rings often hire programmers to write custom threats which enable the ring to steal private information for their own gain or to be sold on the black market.

It can be very difficult for even IT professionals to remove Malware infections, therefore focusing on prevention rather than reaction is strongly recommended.