A search engine is an information retrieval system that allows someone to search the vast collection of resources on the Internet and the World Wide Web. All major search engines are similar in that keywords, phrases, or in some instances, questions, are entered in a search form. After clicking on the search command button, the database returns a collection of hyperlinks to resources that contain the search terms. These hyperlinks are listed in some sort of order, usually from most relevant to least relevant, or by how important the web pages are, depending on the search engine used. Search engines are composed of computer programs that create databases automatically. They should not be confused with human-built directories, such as Yahoo!, which depend on people for development and maintenance.

Search Engine Basics

Search engines have three components. The first part is a computer program called...