Antivirus software consists of computer programs that attempt to identify, thwart and eliminate computer viruses and other malicious software (malware). Antivirus software typically uses two different techniques to accomplish this:

1. Examining (scanning) files to look for known viruses matching definitions in a virus dictionary.
2. Identifying suspicious behavior from any computer program which might indicate infection. Such analysis may include data captures, port monitoring and other methods.

Here are leading Antivirus Software and ranking of their portals based on anti virus protection Google page rank and anti virus protection Alexa Traffic rank.

Symantec - Makers of popular Norton Antivirus product.

Sophos Anti-Virus - Antivirus software package targeted at business customers

F-Secure - Anti-virus and anti-intrusion software designed for both home and corporate users.

Kaspersky Lab - Makers of Kaspersky Anti-Virus and related security products (Formerly known as AVP)

McAfee.com - Produces the McAfee VirusScan line of antivirus software, as well as various specialized products for home and business users. Also offers managed security services for home and business users.

Clam AntiVirus - Toolkit for UNIX systems released under GPL. Provides a scanning daemon intended primarily for mailserver integration, command line scanner for on-demand scanning, and update tool.

Symantec Removal Tools - Freeware executables designed to remove specific viruses from a system.

BullGuard - Software featuring combined firewall, anti-virus, spam, and backup programs.

ALWIL Software - avast! complete anti virus protection for all computers with a fast incremental update. Several versions available Home, Professional, Network, Enterprise, Groupware, and Firewall edition.

Norman ASA - Anti-virus software, personal firewall, risk analysis, encryption, data recovery and certified data erasure.

Declude Virus - Mail server virus and vulnerability control software.

BitDefender - Offers a variety of antivirus products, including specialized handheld device, peer-to-peer, and email scanners

Central Command, Inc. Company markets Vexira Antivirus software as well as: virus protection consulting, implementation, and audit services. Free trial virus protection downloads and up-to-date virus information.

List of Anti Virus Protection Softwares