A virus is a self replicating program that can destroy or cause damage to data stored on a computer system.

A virus program must be executed in order to infect a computer system. Viruses can attach themselves to other programs in order to ensure that this happens. Viruses are spread through file downloads or infected storage media such as floppy disks.

Common symptoms of virus infection:

• Displaying unwanted messages
• Unusual visual or sound effects
• Loss of data from a storage medium
• Computers restarting unexpectedly
• Unwanted generation of e-mails