A Google product which allows website owners to place ads from the Google Adwords network on their site (as well as in feeds, mobile apps, videos and YouTube content) and receive payment for clicks on those ads.
After being accepted into the program, site owners use an online form to generate JavaScript code that is placed on their pages to deliver the ads. Adsense then serves targeted ads to the site based upon the content of the pages the ads appear on. Site owners are paid based upon either the number of clicks on an ad (pay-per-click) or the number of ad impressions depending upon the ads displayed.
Adsense revenues are over $12 billion annually and account for roughly one quarter of Google’s revenue.