Pay-Per-Click
(pay-per-click, payperclick)

A Pay-Per-Click search engine enables you to list your site at the top of the search engine results for a particular keyterm if you are willing to pay (through an auction process) for each time someone clicks on that listing.

The Pay-Per-Click listings are usually marked as different from non-paid search listings (e.g. Sponsored Links). There are usually 3-4 listing spots available at the top of a page for a given keyterm. Each keyterm is sold separately and positions are influenced by how much you are willing to pay per click.