Antivirus (or anti-virus) software is a type of security software that is designed to protect computer systems and networks from malicious software (malware) such as viruses, worms, Trojan horses, and other types of malicious software.

Antivirus software works by scanning files and system memory for known malware signatures, which are patterns of code that are unique to specific malware. The software can also use heuristics and behavioral analysis to detect previously unknown malware by looking for suspicious behavior or activity.