A computer worm is a virus that spreads by creating duplicates of itself on other drives, systems or networks. Computer worms may send copies of themselves to other computers across network connections, through email, through an infected Web page or through instant messages and Internet Relay Chat (IRC). Some computer worms are differentiated as being "@m" or "@mm", which signifies that their primary distribution method is through electronic mail or mass-mail.What is a a computer worm?How do you know if your PC has a worm?
  • There are new icons or shortcuts on your desktop that were not previously there.
  • Your PC is noticeably slow.
  • You receive annoying pop-ups that appear on a regular basis.

How do you avoid computer worms?
  • Don't download files from unknown sources, either from your email or a website.
  • Scan all new files with virus-scanning software before opening.
  • Check for any virus-scanning software updates.
  • Don't download attachments (e.g., pictures, games, electronic greetings) unless it's from someone you know.
  • Notify someone if you are planning on sending an email with links or attachments.
  • Turn on your firewall to alert you of any harmful sites you may come across while surfing the internet.
  • Safeguard important files and communications by creating a strong password and changing it frequently.
What do you do if your computer has a worm?
If you think your computer has a worm, we recommend that you use antivirus software to run a scan. If you don't have one, you can download McAfee's latest antivirus software or you can visit AOL's Internet Security Central page for more information.


(Source: http://www.pcsecurityalert.com/pcsecurityalert-articles/computer-worms.htm)