What is a Computer Virus?

A computer virus is an executable program that may cause damage to the contents of your hard disk and/or interfere with the normal operation of your computer.

By definition, a virus program is able to replicate itself. In most cases, if a file containing a virus is executed or copied to another computer, the other machine will also be “infected”. A virus can be introduced to a computer system with any software program. For internet users, this threat can come from downloading files through a File Transfer Protocol (FTP) or email attachments.

A virus can attach itself to, or sometimes even replace, an existing program. When the user runs the program in question, the virus is also executed. This usually happens without the user being aware of it.

A virus program contains instructions to initiate some sort of “event” that affects the infected computer. Each virus has an unique event associated with it. These events and their effects can range from harmless to devastating. For example:

  • An annoying message appearing on the computer screen.
  • Reduced memory or disk space.
  • Modification of data.
  • Files overwritten or damaged.
  • Hard drive erased.