A virus is a program that can cause damage to a computer and can replicate itself in a computer and over the network or internet. Virus code is usually buried within the code of another program.

A worm is self-contained program (or set of programs) that is able to spread copies of itself to other computer systems. The propagation usually takes place through network connections or email attachments.

How do you defend yourself against Viruses & Worms?  Watch the following video, Defend Yourself Against Virus & Worms from OnGuardonline.gov