You know you have adware installed when advertisements keep popping up on your computer. Some adware programs can monitor your Internet surfing to target the Websites that you log on to, and then generate automatic pop-up advertisements based on your viewing habits. They are also called spyware, and are more difficult to track and find. Adware is often included automatically without you knowing it when you download from certain Websites and free applications. When you click on a link to download a program, you often unwittingly give permission to download adware or spyware. Media companies pay publishers of freeware programs to include adware in their free downloads. These programs run in the background when you are online, and they can slow down your computer and affect its performance.

You can try to remove adware programs with the Add/Remove function on your control panel. This doesn't always work, because you have to be able to recognize the name of the adware program. There are programs that can remove adware and spyware from your computer and some of them are free, such as Ad-Aware and Spybot. Some Internet providers include protection against adware and spyware, and some anti-virus programs can detect and delete adware. You can also install free pop-up blockers, so deceptive pop-ups, which may include potentially harmful links, won't appear in the first place. There are a lot of tricks involved in these programs, so if you do click on a link to download a program, make sure you pay attention to the dialog box and recognize the publisher before you click "yes," to avoid downloading a program that you didn't ask for or that may be dangerous for your computer.