Google AdSense is a program run by Google through which website publishers in the Google Network of content sites serve text, images, video, or interactive media advertisements that are targeted to the site content and audience. These advertisements are administered, sorted, and maintained by Google. They can generate revenue on either a per-click or per-impression basis. Google beta-tested a cost-per-action service, but discontinued it in October 2008 in favor of a DoubleClick offering. In Q1 2014, Google earned US$3.4 billion, or 22% of total revenue, through Google AdSense. AdSense is a participant in the AdChoices program, so AdSense ads typically include the triangle-shaped AdChoices icon. This program also operates on HTTP cookies. In 2021, over 38.3 million websites use AdSense.