How Adware Works
Adware spies on users and tries to display adverts based on a user's browsing habits. The software will examine words typed by the user into search engines and also the type of web pages a user visits. The software will then display adverts that will be of interest to the user.
Note: This type of advertising should not be confused with legitimate advertising that commercial interests pay for to appear on popular web sites.
Click on this link to read more about adware: