Pay-per-click (PPC) (also called cost per click) is an internet advertising model used to direct traffic to websites, in which advertisers pay the publisher (typically a website owner) when the ad is clicked. Farris et al have defined it simply as “the amount spent to get an advertisement clicked. ” With search engines, advertisers typically bid on keyword phrases relevant to their target market. Content sites commonly charge a fixed price per click rather than use a bidding system.