Google AdSense, frequently just AdSense, is an ad serving program run by Google. Website owners can enroll in this program to enable text, image and, more recently, video advertisements on their sites. These ads are administered by Google and generate revenue on either a per-click or per-thousand-impressions basis. Google is also currently beta-testing a cost-per-action based service. Overview
The underlying technology behind AdSense was derived originally from WordNet, Simpli (a company started by the founder of Wordnet, George A. Miller) and a number of professors and graduate students from Brown University, including James A. Anderson, Jeff Stibel and Steve Reiss. A variation of this technology utilizing Wordnet was developed by Oingo, a small search engine company based in Santa Monica founded in 1998. Oingo changed its name to Applied Semantics in 2001, which was then bought by Google for $102 million in April 2003. 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".AdSense for feeds works by inserting images into a feed. When the image is displayed by the reader/browser, Google writes the ad content into the image that it returns. The ad 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 site in the same way as regular AdSense ads.AdSense for feeds has remained in its beta state ever since its original announcement. Only selected AdSense users have been allowed to sign up for it, and no more users are being admitted to the program. AdSense for search
A companion to the regular AdSense program, AdSense for search lets website owners place Google search boxes on their pages. When a user searches the web or the site with the search box, Google shares any ad revenue it makes from those searches with the site owner. However the publisher is paid only if the ads on the page are clicked: Adsense does not pay publishers for mere searches. XHTML Compatibility
As of September 2007, the HTML code for the AdSense search box does not validate as XHTML, and does not follow modern principles of website design:
Some webmasters create sites tailored to lure searchers from Google and other engines onto their AdSense site to make money from clicks. These "zombie" sites often contain nothing but a large amount of interconnected, automated content (e.g.: A directory with content from the Open Directory Project, or scraper sites relying on RSS feeds for content). Possibly the most popular form of such "AdSense farms" are splogs ("spam blogs"), which are centered around known high-paying keywords. Many of these sites use content from other web sites, such as Wikipedia, to attract visitors. These and related approaches are considered to be search engine spam and can be reported to Google.MFA (Made For AdSense) is a site or page with little or no content, but filled with advertisements so users have no choice but to click on ads. Such pages were tolerated in the past, but due to complaints Google now disables such accounts.There have also been reports of Trojans engineered to produce fake Google ads that are formatted to look like legitimate ones. The Trojan Horse apparently downloads itself onto an unsuspecting computer through a web page and then replaces the original ads with its own set of malicious ads. Criticism
Due to concerns about click-fraud, Google AdSense has been criticized by some search engine optimization firms as a large source of what Google calls "invalid clicks" in which one company clicks on a rival's search engine ads to drive up its costs. Some publishers that have been blocked by Google complain that little justification or transparency was provided. Webmasters who publish AdSense can receive a lifelong ban without justification. Google claims they can't "disclose any specific details" on fraudulent clicks since it may reveal the nature of their proprietary click-fraud monitoring system.To help prevent click-fraud, AdSense publishers can choose from a number of click-tracking programs. These programs will display detailed information about the visitors who click on the AdSense advertisements. Publishers can use this to determine if they have been a victim of click-fraud or not. There are a number of commercial tracking scripts available for purchase.The payment terms for webmasters have also been criticized. Google withholds payment until an account reaches US$100, but many small content providers require a long time – years in many cases – to build up this much AdSense revenue. These pending payments are recorded on Google's balance sheet as "accrued revenue share". At the close of its 2006 fiscal year, the sum of all these small debts amounted to a little over $370 million, cash that Google is able to invest but which effectively belongs to webmasters. However, Google will pay all earned revenue greater than $10 when the AdSense account is closed.Google recently came under fire when the official Google AdSense Blog showcased the French video site Imineo.com. This site clearly violates Google's AdSense Program Policies by displaying AdSense alongside explicit adult content. Typically, sites displaying AdSense have been banned from showing adult content. In addition, Google has been criticized for claiming that they created, or had a bigger part in creating, AdSense than they really did. Most recently, Gokul Rajaram claiming he was the "godfather" of AdSense caused some controversy. A further Google employee who took credit for AdSense was Susan Wojcicki.
Resource: Part or all of the information provided in this section is brought to you via wikipedia and other similar sites. Please repsect their licenses and for more information visit the homepages of these sites.