Search Engine is a tool designed to search for information on the internet. Search engine technology tracks its roots to web directories, websites that were originally used for organizing information. Search engines allow users to look for information within pages of other websites and not just title or category as was the case with web directories.Search engines' revenue comes from advertisements that are sold to advertisers and displayed alongside the natural (or organic) search results. Ads are generally sold by having advertisers bid on keywords or search terms of interest and are in most cases paid for on a Cost Per Click basis, meaning that the advertisers pays every time a search engine user clicks on an ad.It is a misconception that end-users using a search engine are their customers. In fact search engine users are search engine's product, since a true customer of a search engine is the advertiser.