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A computer virus is a program that attaches itself to the executive files such as .com and .exe or the system areas of hard disk and floppy disks and then make copies of itself. Viruses usually operate without being acknowledged by a computer user.
An Anti-virus program provides a layer of security to protect the user from a computer virus and Trojan horses. To avoid virus infections in your computer, install anti-virus software from a well-known, reputable company and update it regularly.
Examples of such companies are McAfee VirusScan, Norton AntiVirus, Panda Antivirus Suite, F-Secure Anti-Virus, Kaspersky Anti- Virus, MIMESweeper(mail firewall), Norman Virus Control and Trend PC-cillin.