Spyware is often associated with software that displays advertisements (called adware) or software that tracks personal or sensitive information. That does not mean all software which provides ads or tracks your online activities is bad. For example, you might sign up for a free music service, but "pay" for the service by agreeing to receive targeted ads. If you understand the terms and agree to them, you may have decided that it is a fair tradeoff. You might also agree to let the company track your online activities to determine which ads to show you.

Other kinds of unwanted software will make changes to your computer that can be annoying and can cause your computer slow down or crash. These programs have the ability to change your Web browser's home page or search page, or add additional components to your browser you don't need or want. These programs also make it very difficult for you to change your settings back to the way you originally had them. These types of unwanted programs are also often called spyware.