||A viewer requests a page from a website.
||The website returns the page which includes embedded links to the ads
||Just like obtaining images for a page, the browser will obtain the ads from the ad server. The URL provided identifies the original website and perhaps a given session. Cookies placed by the ad service identify the viewer to varying degrees of accuracy.
||The ad is returned to the viewer.
||Behind the scenes aggregate data from the various monitoring sources are used to select the best ad to deliver. Delivered ads provide additional information about the user for the future.