Worm
Computer worms are viruses that reside in the active memory of a computer and duplicate themselves. They may send copies of themselves to other computers, such as through email or Internet Relay Chat (IRC). A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security holes, and then starts replicating from there, as well.
