What Is PPC
Pay per click or PPC is an Internet advertising model used to direct traffic to websites, where advertisers pay the hosting service when the ad is clicked. With search engines, advertisers typically bid on keyword phrases relevant to their target market.
The three largest PPC providers are Google AdWords™, Yahoo!™, and Microsoft AdCenter™.
Here are several valuable links for understanding PPC Marketing.
Understanding Search Engine Marketing on Google
Understanding Google Quality Score