Pay-per-click advertising, also known as PPC, is largest and most popular form of Online advertising where advertisers have nothing to pay for advertising their websites but they have to pay per each click that site visitors made on their link. This advertising procedure is also called Cost per Click (CPC) advertisement and it is an Internet advertising model which used to direct traffic to websites, where advertisers pay the publisher when the ad is clicked and it is used on search engines, advertising networks, and content sites, blogs, forums etc.