Contextual advertising is a form of advertising which focuses on a special keyword or text on a web page or any media for displaying ads. This works by finding out what the user wants from the web page. There are two types of context advertisements. They are Static context advertisement and dynamic context advertisement. The former type was being used before but the latter form is being used extensively now a days. In dynamic context advertising, the advertisements change with the contents of the page. This would increase the probability of clicks on the ads. For instance, if the user is viewing information of food, the ads appearing on the context advertising section would display links related to food companies and types, classification. The idea of contextual advertising came from the fact that when the advertisements are not related to the user’s interest, the clicks on the ads would be less and therefore generating lower revenue. Search Engines use contextual ads section to display the ads relevant to the users search. The keywords are discovered by mining the data on the content page. Search engines use the keywords provided by the user for the search. This would optimize the search criteria and speed up the process.