AdSense Summary

AdSense is a way of extending Google's core advertising program, AdWords, to non-Google sites. (Google refers to these sites as its "content network".)

The way it works is fairly simple:

• Advertisers submit ads to Google using the AdWords program. They create small text ads and give Google a maximum per-click price for the ads based on which keywords the advertisers are interested in.
• A website owner interested in making extra money joins Google's AdSense program. After being accepted, Google supplies the owner -- now called an AdSense publisher -- with some custom JavaScript code to place on the website's pages.
• The first time a page is loaded after the code is placed on it, Google sends out its crawlers to fetch a copy of the page for analysis. Sophisticated algorithms (described in the AdSense patent) determine the general topic of the page and what keywords are associated with that topic.
• Once the page is analyzed, Google can select ads from the pool of AdWords-supplied advertisements to display on the page. The ads are selected based on the keywords determined from the analysis step. An auction system is used to select which specific ads to display based on various metrics, such as maximum bid price and how successful the ads are at attracting clicks.
• The ads are displayed along with the page content. The publisher can adjust some of the ad settings, such as the layout of the ads and the colors used by the ads, to better blend the ads with the page.
• Whenever a visitor clicks one of the ads, Google debits the advertiser's AdWords account a value no more (and usually less) than the advertiser's maximum bid price for the ad. The visitor who clicked the ad is sent to the advertiser's landing page.
• Google then shares a percentage of the advertiser's per-click payment with the AdSense publisher whose site displayed the advertisement.

If you're an AdSense publisher, then, what you're really doing is renting space on your web pages to Google. Google displays ads in that space and shares the revenue it makes from those ads with you in return for the use of the space. A very simple model, but with lots of interesting and sophisticated technology to support and maintain it.

If you have a website already and are looking to monetize it, I highly recommend you join Google's AdSense program!