Search engine advertising is when the client of the search engine pays for appearing on the page of results. The applicants of this service will have to purchase the key words or phrases. Those advertisements will appear in small text form along the side and the top of the search results (refer to image provided earlier). The rankings of the advertisements are depended on how much the applicants are bidding for every person that clicks on the link and the click rate of the link (calculated by the number of people who clicks on the link divided by the number of people who sees the link). These are called the Cost-per-Click services provided by the search engines.