Pay-Per-Click (PPC) and Cost-Per-Click (CPC)
The terms PPC and CPC are often used interchangeably. PPC advertising is cost effective way of driving traffic to your site. The process occurs just as it sounds, each ad click accrues a small cost. The costs of this exchange are selected by you or your business, and often are bid on in accordance.
To put this into perspective, say you sell Rolex Watches, and you have decided that you are willing to pay $5.00 per click at maximum. This value is only paid if the person in the bid position rank just below you is willing to $4.99. Multiple factors go into this positioning, not just money, there is also a content score and a formatting score. Thus, a person with excellent content and proper formatting, may rank higher than you with a lower bid being placed.
Click here for more on PPC just select the link.