If your computer performs abnormal operations such as popping up weird toolbars in the browser, opening up too many pop-up windows, or if your homepage changes without notification, then your computer has been infected by a Spyware. This is a serious problem since this kind of spy softwares invades your personal privacy, seriously damaging you computer and causing even loss on your business.
The Spyware softwares often install additional programms in your computer without your consent. These softwares may monitor your activity on the Internet, track the addressees of the people you send e-mails to, and even see your IMs. Hackers monitor and gather all your passwords, visited applications and web pages, and also personal data such as credit card numbers.