Pay for placement

Pay for placement, or P4P, is an Internet advertising model in which advertisements appear along with relevant search results from a Web search engine. Under this model, advertisers bid for the right to present an advertisement with specific search terms (i.e., keywords) in an open auction.^[1] When one of these keywords is entered into the search engine, the results of the auction on that keyword are presented, with higher ranking bids appearing more prominently on the page.

When P4P was first introduced, controversy arose because seventy percent of Internet users were unaware that search results could be skewed as a result of such agreements,^[2] which in some cases led to legal action.^[3] Many users felt that the search results would be irrelevant; however, the auction model has proven to be effective at producing relevant results for searches where the user wants to purchase something.^{[citation needed]} P4P is now seen as the most efficient and effective way to monetize search engines.^{[citation needed]}