Contextual Advertising: Unlike traditional online advertising, which displays the same ads to all users, contextual advertising delivers targeted advertising to users based on their browsing habits or other information.
This form of advertising tends to have a more direct link of the type of content being viewed on a website. For instance, a person looking at a fashion website might see advertising for clothing and accessories, rather than ads for unrelated products. For this reason, contextual advertising is sometimes referred to as "in-text" or "in-context" advertising.
For search engines, Google AdSense was one of the first contextual advertising platforms available. The ads' content relies on user's keywords used in their Google searches; with each search, relevant ads are displayed above or to the side of search results.
Other examples of contextual advertising that target users could include the advertisements on a video website like Hulu. The site's advertisers might take information from a user's watching habits or ads they've indicated a preference for and only show ads for specific companies and/or products. Some websites, like Facebook, will also use information from previous browsing or search habits and develop advertising based on that data. While some privacy advocates are opposed to such methods, advertisers argue that they help generate most useful leads online.