A computer is a machine. It handles a lot of information. Many people use computers to help them work better. Unfortunately, many computers are often hurt by virus. A computer virus is a set of bad instructions written just to hurt computers. The virus is made by someone and sent to computers. It is set to turn on by itself. When it does, many computers around the world begin to have problems. When the virus is turned on, it makes the computer do things it is not supposed to do. Many computers start to fill up with a lot of useless information. Several computer projects which have already spent millions of dollars are in great trouble. When the computers are invaded by a virus, some people have to turn off their computers; others have to stop their computers from being connected to other computers. The virus is spread by having computers share information with each other. Once in the computer, it takes over and tells the computer to do harmful things.