Spyware
It spy's on you
spyware
spyware spy's on you in the background it could just watch what you do to know what ads to send to you or it can steal personal data like bank account numbers and your identity
how to avoid spyware
don't click links with pop ups, because pop windows are often a product of spyware
spyware prevention
Barracuda is a service that can prevent spyware
McAfee claims to be anti virus its bloatware