Pay per click search engines, pay for placement or pay for ranking search engines, are a highly cost-effective way to attract website visitors and targeted website traffic

Pay Per Click (also known as Pay Per Ranking, Pay Per Placement or Pay Per Position) enables you to list your site at the top of the search engine results by advertising on keywords that best describe your product or service.

The higher you bid, the higher your advertisement will be displayed in the list. You pay only when a searcher or clicker clicks on your listing to look at your website.   You don't pay to list, you only pay for clicks or click throughs. This way you only pay for the traffic to your site, there are no other hidden costs.

A PPC listing on a search engine results page typically consists of a title, which usually is your website's name or perhaps a short heading (around 50 characters maximum) and also a short (usually no more than 200 characters long) description of your service or some promotional wording.
 
Some search engines strictly control the text that can appear in the listing, while others are more open to using the advertiser's own text.
 
The actual cost of such advertising really does depend upon how popular or how competitive your "target keyword" or "key phrase" is.