Google AdSense is an
advertisement serving program run by
Google.
Website owners can enroll in this
program to enable text, image, and more recently, video
advertisements on their websites. These advertisements 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.
OverviewGoogle uses its
Internet search technology to serve advertisements based on website content, the user's geographical location, and other factors. Those wanting to advertise with Google's targeted advertisement system may enroll through
AdWords. AdSense has become a popular method of placing advertising on a website because the advertisements are less intrusive than most
banners, and the content of the advertisements is often relevant to the website.
Currently, AdSense uses
JavaScript code to incorporate the advertisements into a participating website. If the advertisements are included on a website that has not yet been
crawled by the
Mediabot, AdSense will temporarily display advertisements for
charitable causes, also known as
public service announcements (PSAs). (The Mediabot is different from the
Googlebot, which maintains Google's search index.)
Many websites use AdSense to
monetize their content. AdSense has been particularly important for delivering advertising revenue to small websites that do not have the resources for developing advertising sales programs and salespeople. To fill a website with advertisements that are relevant to the topics discussed,
webmasters implement a brief script on the websites' pages. Websites that are content-rich have been very successful with this advertising program, as noted in a number of publisher
case studies on the AdSense website.
Some webmasters invest significant effort into maximizing their own AdSense income. They do this in three ways.
They use a wide range of traffic-generating techniques, including but not limited to online advertising. - They build valuable content on their websites that attracts AdSense advertisements, which pay out the most when they are clicked.
- They use copy on their websites that encourages visitors to click on advertisements. Note that Google prohibits people from using phrases like "Click on my AdSense ads" to increase click rates. The phrases accepted are "Sponsored Links" and "Advertisements.
The source of all AdSense income is the AdWords program, which in turn has a complex pricing model based on a Vickrey second price auction. AdSense commands an advertiser to submit a sealed bid (i.e., a bid not observable by competitors). Additionally, for any given click received, advertisers only pay one bid increment above the second-highest bid.
History
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 by Gilad Elbaz. Oingo changed its name to Applied Semantics in 2001, which was later acquired by Google in April 2003 for US$102 million.
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 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 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.
How AdSense works
The webmaster inserts the AdSense JavaScript code into a webpage.
- Each time this page is visited, the JavaScript code creates an IFrame with a src attribute set to the page's URL.
- 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 AdSense patent.)
- For site-targeted advertisements, the advertiser chooses the page(s) on which to display advertisements, and pays based on cost-per-thousand-impressions (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 will be 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.
