What is a worm?

A worm is a virus that spreads by creating duplicates of itself on other drives, systems, or networks. They may send copies of themselves to other computers across network connections, through e-mail, through an infected Web page, or through Instant Messenger and Internet Relay Chat (IRC). Some worms are differentiated as being @m or @mm, which signifies that their primary distribution method is through electronic mail or mass-mail.