Pay per click or PPC is an advertising model on search engines. It is the primary advertising model on search engines and their advertising networks. For most PPC publishers, advertisers bid in an auction-style system to get their ads displayed based on certain keywords or phrases that are relevant to their business and target market.
The ad will then be displayed either when a search keyword matches the advertiser's keyword list, or when a content page displays content relevant to the keyword list. Many publishers differentiate between these paid links and natural content links by calling them sponsored links/ads.