Antivirus software are programs that try to identify, neutralize or eliminate malicious software and scripts. Antivirus is so named because the earliest examples were designed to fight computer vira; however most modern antivirus software is now designed to fight a wide range of threats, including worms, phishing attacks, rootkits, trojan horses and other malware. Antivirus uses two different approaches to accomplish this:

   1. Scanning files to look for known vira matching definitions in a virus dictionary, and
   2. identifying suspicious behavior from any computer program which might indicate infection.

The second approach is called heuristic analysis. Such analysis may include data captures, port monitoring and other methods.

Most commercial antivirus uses both of these approaches, with an emphasis on the virus dictionary approach. Some claim that a Firewall program performs the functions of a AntiVirus. But this is not the case.