Computer code(program) designed to control some part of your computer in some way. Usually runs in the background on your PC. They usually attach themselves to a legitimate program. Some rewrite information in the MBR (master boot record) so the PC will need to be totally reloaded. Sometimes all your data is lost. Some send emails with themselves attached, can delete critical files, and randomly destroy documents. Some are practical jokes. All use PC resourses.

Runs in the background on your PC and reports information back to a internet server (ET call Home). Information can be sites you visit, programs you run, and possibly keystrokes of data you enter. All use PC resourses.

Nagging screen pop-ups that are related to Spyware. Usually the product of information that was collected by Spyware.

These can be related to spyware, but seem like some neat items to keep you informed. WeatherBug is one of these. Most are deigned to work within Internet Explorer and other screen interfaces. These may be neat, but they slow down your PC and may contain a virus or Spyware. All use PC resourses. Plug-ins from Microsoft and other software venders are legitimate.

Web pages that try to fool you into giving out your personal information so it can be captured. They replicate a legitimate web page and try to get you to login with your user name and password. Is a identity thief.

Some Pop-ups have a Red X imposter. What happens is when you click the Red X on the Pop-up to close it, you go to another web site.

Emails disguised as official messages from companies with which you do business, and ask you to submit sensitive personal information by email, fax, or a fake Web site -- with the intent to steal your identity. These "phisher" emails and Web sites often mimic the logos, colors, and language used by legitimate companies and can be very convincing.