To learn more about using subject headings click here . Webcrawler , Lycos , and Alta Vista are search engines . They use a computer program called a spider to automatically search the World Wide Web for new sites and add them to the engine s database as they are found or as sites are submitted to them. They index words found within the contents of Websites and when you make your search, the words you use are compared to the index, and the pages retrieved. The more the word is used in the page, where it is in the page, and other factors, make the page appear higher on your hit list.
Search engines search the entire contents of millions of Web pages.
Search engines are best used when searching for specific words or phrases within Web sites. This means one search will be sent to several subject guides and search engines simultaneously and the results compiled for you. Useful, but use with caution as they can miss pages you may be interested in. Google uses link popularity as a way to rank web sites. Web users have voted for good sites by linking to them.