Malware (Malicious Software) is software which intends to access, damage, or destroy computers without the owner’s consent and/or knowledge. Malware can take many forms (virus, spyware, trojans, worms, etc.) and can infect any type of computer system, including but not limited to hard drives, servers, clients, and other computer networks.
Because malware can be difficult to eliminate after it has infected a system, and effective prevention strategy is the best countermeasure. An effective prevention strategy should include strong anti-malware software usage along with smart browsing techniques and download analyses.
Five of the Worst Computer Viruses Ever: