Delivering ads to users based on their preferences. Adware programs analyze a user's Web surfing habits to determine the type of merchandise they are likely to purchase. As a result of the analysis, "contextual ads" are made to pop up periodically. Contextual marketing is widely implemented by search engines. They display ads on the results pages based on the key words users enter for a search. In addition, contextual marketing is available for websites in general. The service offers to place ads on pages that are geared to the audience likely to visit the site. See adware.