Antivirus software works by scanning files and programs on a computer system to detect and remove malicious software, such as viruses, worms, trojans, and other forms of malware. It uses various techniques like signature-based scanning, heuristic analysis, and behavioral monitoring to identify and quarantine or remove malicious code. Antivirus software also often includes features like real-time protection, automatic updates, scheduled scanning, and quarantine management to provide continuous protection against emerging threats and suspicious activities.