Understanding Search Engines
•Some search engine operators sell paid placement rights on results pages.  These paid placement links are often labeled as “sponsored,” and they are usually called sponsored links.
•If the advertising appears in a box on the page (usually at the top, but sometimes along the side or bottom of the page), it is usually called a banner ad.
•Revenue from sponsored links and banner ads is used to generate profit after covering the costs of maintaining the computer hardware and software required to search the Web and to create and search the database.