Google AdSense is an ad-serving program operated by Google that provides relevant text, image, and video-based advertisements to enrolled site owners. Advertisers register via Google AdWords and pay for ads on a Pay-Per-Click, Cost-Per-Thousand or Cost-Per-Action sordid. This revenue is shared with Google AdSense legion sites, typically on a PPC groundwork (which sometimes leads to Click Fraud). Google uses its search Algorithms and Contextual Link Inventory to display the most appropriate ads based on site content, Query relevancy, ad "quality scores," and other factors.