Understanding Search Engines
•A web search engine is a Web site (or part of a Web site) that finds other Web pages that match a word or phrase you enter.
 •The word or phrase you enter in a search engine is called a search expression or a query.
 •A search expression or query might also include instructions that tell the search engine how to search. 
•A search engine does not search the Web to find a match; it searches only its own database of information about Web pages that it has collected, indexed, and stored.