How AdSense Works

• The webmaster inserts the AdSense JavaScript code into a webpage.
• Each time this page is visited, the JavaScript code uses inlined J SON to display content fetched from Google's servers.
• For contextual advertisements, Google's servers use a cache of the page to determine a set of high-value keywords. If keywords have been cached already, advertisements are served for those keywords based on the AdWords bidding system. (More details are described in the Ad Sense patent.)
• For site-targeted advertisements, the advertiser chooses the page(s) on which to display advertisements, and pays based on cost per mille (CPM), or the price advertisers choose to pay for every thousand advertisements displayed.
• For referrals, Google adds money to the advertiser's account when visitors either download the referred software or subscribe to the referred service^. The referral program was retired in August 2008.
• Search advertisements are added to the list of results after the visitor performs a search.
• Because the JavaScript is sent to the Web browser when the page is requested, it is possible for other website owners to copy the JavaScript code into their own webpages. To protect against this type of fraud, AdSense customers can specify the pages on which advertisements should be shown. AdSense then ignores clicks from pages other than those specified.

AdSense for Video

AdSense for video allows publishers with video content to generate revenue using ad placements from Google's extensive advertising network including popular YouTube videos

AdSense for Domains

AdSense for domains allows advertisements to be placed on domain names that have not been developed. This offers domain name owners a way to monetize domain names that are otherwise dormant or not in use. AdSense for domains is currently being offered to all AdSense publishers, but it wasn't always available to all.
On December 12, 2008, TechCrunch reported that AdSense for Domains is available for all US publishers.
On February 22, 2012, Google announced that it was shutting down its Hosted AdSense for Domains program.

AdSense for Mobile Content

AdSense for mobile content allows publishers to generate earnings from their mobile websites using targeted Google advertisements. Just like AdSense for content, Google matches advertisements to the content of a website — in this case, a mobile website. Instead of traditional JavaScript code, technologies such as Java and Objective-C are used

AdSense for Search

A companion to the regular AdSense program, AdSense for search, allows website owners to place Google Custom Search boxes on their websites. When a user searches the Internet or the website with the search box, Google shares 51% of the advertising revenue it makes from those searches with the website owner.^[5] However the publisher is paid only if the advertisements on the page are clicked; AdSense does not pay publishers for regular searches. Web publishers have reported that they also pay a range from $5.67 to $18.42 per click

AdSense for Feeds

In May 2005, Google announced a limited-participation beta version of AdSense for Feeds, a version of AdSense that runs on RSS and Atom feeds that have more than 100 active subscribers. According to the Official Google Blog, "advertisers have their ads placed in the most appropriate feed articles; publishers are paid for their original content; readers see relevant advertising—and in the long run, more quality feeds to choose from."^[12]
AdSense for Feeds works by inserting images into a feed. When the image is displayed by a RSS reader or Web browser, Google writes the advertising content into the image that it returns. The advertisement content is chosen based on the content of the feed surrounding the image. When the user clicks the image, he or she is redirected to the advertiser's website in the same way as regular AdSense advertisements.
AdSense for Feeds remained in its beta state until August 15, 2008, when it became available to all AdSense users

AdSense for Content

The content-based adverts can be targeted for interest or context. The targeting can be CPC (click) or CPM (impression) based. There's no significant difference^[11] between CPC and CPM earnings, however CPC ads are more common. There are various ad sizes for available for content ads. The ads can be simple text, image, animated image, flash, video, or rich media ads. At most ad sizes, users can change whether to show both text and multimedia ads or just one of them. As of November 2012, a grey arrow appears beneath AdSense text ads for easier identification.