Virus protection software is designed to prevent viruses, worms and Trojan horses from getting onto a computer as well as remove any malicious software code that has already infected a computer.
Most virus protection utilities now bundle anti-spyware and anti-malware capabilities to go along with anti-virus protection. Internet security suites go a step further by including additional capabilities like anti-spam, anti-phishing, firewall, file protection and PC optimization.
Also see antivirus programs and The Difference Between a Virus, Worm and Trojan Horse in the Did You Know? section of Webopedia.