Search engines are software tools that allow a user to ask for a list of Web pages containing certain words or phrases from an automated search index. The automated search index is a database containing some or all of the words appearing on the Web pages that have been indexed. The search engines send out a software program known as a spider, crawler or robot. The spider follows hyperlinks from page to page around the Web, gathering and bringing information back to the search engine to be indexed.
Most search engines index all the text found on a Web page, except for words too common to index, such as "a, and, in, to, the" and so on. When a user submits a query, the search engine looks for Web pages containing the words, combinations, or phrases asked for by the user. Engines may be programmed to look for an exact match or a close match (for example, the plural of the word submitted by the user). They may rank the hits as to how close the match is to the words submitted by the user.
One important thing to remember about search engines is this: once the engine and the spider have been programmed, the process is totally automated. No human being examines the information returned by the spider to see what subject it might be about or whether the words on the Web page adequately reflect the actual main point of the page.
Another important fact is that all the search engines are different. They each index differently and treat users' queries differently (how nice!). The burden is on the searcher to learn how to use the features of each search engine. See the links to Search Engines (p. 51) and to sources which have done evaluations of the various features of Web directories and search engines (http://www.ipl.org/-teen/aplus/linksother.htm#interpret).
Read an excellent article about search engines:
"Searching the Internet Part I: Some Basic Considerations and Automated Search Indexes" in InterNICNews, September 1996, by Jack Solock (Solock 1996 A) at:
Also see the Web and internet tutorials (http://www.ipl.org/teen/aplus/-linksother.htm#web) for additional online articles.
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