A pay-per-click search engine is one that allows individuals (advertisers) to pay for positioning in search results. Each time someone clicks through to the listed web site, the search engine charges the advertiser. Ads are usually displayed at the top, side, and sometimes bottom of the page, and indicated as Sponsored Results.
Kathy Barta – Blizzard Internet Marketing, Inc.
The PPC model in search engines is also keyword phrase focused. Other advertising sources offer a PPC model at a “niche directory” level. http://www.inns.com and http://www.vamoose.com for example.