The concept is really simple, if you think about it. The publisher or the webmaster inserts a java script into a certain website. Each time the page is accessed, the java script will pull advertisements from the Adsense program. The ads that are targeted should therefore be related to the content that is contained on the web page serving the ad. If a visitor clicks on an advertisement, the webmaster serving the ad earns a portion of the money that the advertiser is paying the search engine for the click.