Google uses its technology to serve advertisements based on website content, the user's geographical location, and other factors.

AdSense has become one of the most popular programs specializing in creating and placing banner and responsive ads on websites and blogs.

According to Google guidelines on ensuring proper ad placement,[7] advertising and promotional material should not exceed page content.

[10] Google launched its AdSense program, originally named "Content targeting advertising" in March 2003.

[12] Some advertisers complained that AdSense yielded worse results than Google Ads, since it served ads that related contextually to the content on a web page and that content was less likely to be related to a user's commercial desires than search results.

[13] Paul Buchheit, the founder of Gmail, had the idea to run ads within Google's e-mail service.

But he and others say it was Susan Wojcicki, with the backing of Sergey Brin, who organized the team that adapted that idea into an enormously successful product.

[14] By early 2005 AdSense accounted for an estimated 15 percent of Google's total revenues.

[13] In 2009, Google AdSense announced that it would now be offering new features, including the ability to "enable multiple networks to display ads".

In February 2010, Google AdSense started using search history in contextual matching to offer more relevant ads.

As of November 2012[update], a grey arrow appears beneath AdSense text ads for easier identification.

[19] On February 22, 2012, Google announced that it was shutting down its Hosted AdSense for Domains program.

Possibly the most popular form of such "AdSense farms" are splogs (spam blogs), which are poorly written content centered around known high-paying keywords.

These and related approaches are considered to be search engine spam and can be reported to Google.

Such pages were tolerated in the past, but due to complaints, Google now disables such accounts.

There have also been reports of Trojan horses engineered to produce counterfeit Google advertisements that are formatted looking like legitimate ones.

[29] In May 2014, Hagens Berman law firm filed a national class-action lawsuit against Google, claiming the company unlawfully denies payments to thousands of website owners and operators who place ads on their sites sold through Google AdWords.

[30] There were numerous complaints in online discussion forums about a difference in treatment for publishers from China and India, namely that sites from those locations are required to be active for six months before being eligible for AdSense.

[citation needed] Typically, websites displaying AdSense have been banned from showing such content.

For example, in a news story about a terrorist attack in India, an advert was generated for a (presumably non-existent) educational qualification in terrorism.