Google AdSense
AdSense is an advertising program run by Google. Web site owners can enroll in this program to enable text or image advertisements on their sites. These ads are administered by Google and generate revenue on a per-click basis. Google utilizes its search technology to serve ads based on website content, the user's geographical location, and other factors. Those wanting to advertise with Google's targeted ad system may sign up through AdWords.
It currently uses JavaScript code to implement the advertisements into a participating site.