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.

Once the antivirus software detects malware, it can take various actions, such as quarantine the infected files or delete them altogether. Some antivirus software can also automatically clean or repair infected files to remove the malware and restore the file to its original state.

Antivirus software can be installed on individual computers, servers, or network devices, and it can be configured to perform regular scans and updates to ensure that the system is protected against the latest malware threats. Some antivirus software also includes additional security features such as firewalls, email filtering, and web protection to provide a comprehensive security solution.

It's important to note that while antivirus software is an essential component of a comprehensive security strategy, it is not a complete solution. To provide maximum protection against malware, antivirus software should be used in conjunction with other security technologies such as firewalls, intrusion detection and prevention systems (IDS/IPS), and security information and event management (SIEM) systems.