Google AdSense is a program run by Google through which website publishers in the Google network of content sites provide text,
images, video or interactive media ads targeted to site content and audiences. These ads are administered, ranked and maintained by Google.
They can generate revenue on a per-click or per-impression basis. Google beta-tested a cost-per-action service, but discontinued it
in October 2008 in favor of the DoubleClick offering (which is also owned by Google). In Q1 2014, Google generated US$3.4 billion
($13.6 billion annually),or 22% of total revenue, through Google AdSense. AdSense is a participant in the AdChoices program, so AdSense ads