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Resident Virus

Some viruses only attack your system when the program that conceals them is run. Other, more sophisticated, viruses stay in your computer's memory ready to attack anything that is run on the computer. These are resident, or memory-resident, viruses.

The concept of a resident virus is simple. Your computer runs many programs at the same time. This is called multi-tasking. At any moment you may have several programs such as a word processor, a web browser and a media player and many others running simultaneously in your system.

A resident virus is written to work in the same way. Unlike the other programs, however, resident viruses hide in your system. They run whenever something else does, such as when you click a mouse to start a program. In this way they can easily infect other programs.

Next: Virus Quiz 4