Definition of AdSense

AdSense is a program that is run by Google. It is also referred to as Google AdSense. This ad-serving program allows Website owners to make use of advertising images, text ads, and video advertisements on their sites. Administered by Google, the ads generate revenue for the Website owners with a minimum investment in time. Plus, no additional resources are required. The revenue is based upon one of two methods of calculation, per click or per thousand impressions. 

The advertisements are relevant to the content that is maintained on the Website that has signed up to use AdSense. Google’s AdSense automatically delivers ads to your webpages based upon the content that it discovers there. There is no additional effort required on the Website owner’s part. The ads are specifically designed to be relevant to your audience so that they will find them to be useful advertisements rather than annoying bits of information or distracting text or images.

External links:

• A Wikipedia explaination of Adsense
• Google Adsense
• A tour by Google of Adsense
• Google's official Adsense blog
• Webmaster World discussion forums on Adsense