What Is A Search Engine?
Search Engine Defined
A search engine is a mechanism for locating information on the World Wide Web (WWW) by allowing a user to enter queries. The program responds with a list of matches from its database. A relevancy score for each match and a hyperlink to the URL are usually returned. Each search engine uses a different method to determine which sites to list first when you do a search, which is why results can vary so greatly. Search engines create a database of sites using robots which are referred to as spiders, which are indexing programs that search for keywords within a title or text of a web site. You can search the database by entering words or phrases and the search engine returns a list of hits that matches your request. Factors that influence results include the size of the database, frequency of updating, the research capabilities of the robots and the options of a given search engine. Because the Internet is always growing and the fact that each search engine has different capabilities, performing the same search using different search engines will often give you a huge array of results.
Closely related to a search engine, a directory is a hierarchically organized index that allow the user to browse through lists of web sites by category or subject. They are selective databases compiled by human indexers who regularly review the WWW and categorize new web sites. The top level of a directory's hierarchy provides a broad range of very general topics such as art, computers, entertainment, etc. Each of these broad topics are hyperlinks to more specific topics, such as graphical ( a form of art), Macintosh (a type of computer), movies (a form of entertainment), etc. By simply clicking on the category for the topic in which you are interested, you continue to move down through the hierarchy, selecting subcategories and narrowing the search at each level, until you are presented with a list of hyperlinks that pertain to your topic. Yahoo is an example of a directory.
Technical Terminology Of Search Engines
|Boolean Expressions/Queries||Mathmatical expressions used in a search query to help narrow a broad topic. They use the operators AND (+), OR, and NOT (-).|
|Query Syntax||A set of rules describing what makes up a legal query. On some search engines, special symbols may be used in a query.|
|Query||Information entered into a form on a search engine's Web page that describes the information being sought. Note that a query is not usually phrased as a question.|
|Hyperlink||Text and/or graphics on a Web page that will cause the browser to retrieve and display another Web page or graphic.|
|Hit||A URL that a search engine returns in response to a query.-|
|Match||A synonym for hit.|
|Metasearch Engine||A search tool that calls on more than one other search engine to do the actual searching simultaneously. Also referred to as All-In-One-Search Engine.|
|Relevancy Score||A value that indicates how close a match a URL was to a query; usually expressed as a value from 1 to 100 (in percentage %), with the higher score meaning more relevant.|
|Evaluator||The function that assigns relevancy scores to the information retrieved.|
|Gatherer||The indexer (human) or program (robot) that transverses the WWW collecting information about web pages.|
|Indexer||The human or function (program, robot) that categorizes the data obtained by the gatherer.|
|URL||Uniform Resource Locator: aka..A web page address such as, http://www.uwm.edu/~elona.html|
Description Of Some Popular Search Engines & Tips
A combination of a search engine and directory service. Contains a section with links to Frequently Asked Questions (FAQ's), email addresses, current news and company listings.
Considered by many to be the premier search engine, AltaVista is one of the largest and most comprehensive search engines. Fast and excellent for unclear and hard to find subjects. Provides both simple and advanced search screens.
Yahoo, Yet Another Hierarchical Officious Oracle, is the most widely used and consistently highly rated Internet directory. It is a list of web sites submitted by humans and sorted into categories by indexers comprehensive listings which are updated daily which contributes to its popularity. Current news, stock quotes, sports scores, city maps, regional Yahoos, and resources for kids are available.
|Webcrawler is an example of a meta search engine
that searches many other serach engines simultaneously once a query is
submitted. Some of the search options include: search any of the words,
search all of the words, or search as a phrase. The engine's search
results return titles of documents/web page names by default only,
however there is a Select Summaries option on Webcrawler's homepage which
allow you to get more information about the search results.
Other Resources To Using Search Engines
Here are some more useful references and guides to using search engines. Those marked with an asterisk were consulted are used for the creation of this webpage.
http://www.bestweb.net - A listing of Search Engines and which ones to use for specific purposes.. Last Updated on 5/1/98. Single Search. AltaVista. Ask Jeeves for Kids. Galaxy. Go2.com. HotBot. Infoseek. Lycos. MegaWeb. Northern Light...
http://www.realnames.com - A site that searches for information based on use of everyday language.
http://www.searchsecrets.com - A site that gives tips for searching.
http://www.kcpl.lib.mo.us - A guide to using search engines from Kansas City's public libriary system. Includes a review of popular search engines.
http://www.twics.com - A site that lists search engines worldwide.
http://www.zdnet.com - *PC Magazine's homepage. This site has numerous refrences covering just about every aspect of searching on the WWW.
*Greenlaw, Raymond and Ellen Hepp. Inline / Online: Fundamentals of the Internet. Textbook covering introductory topics to the Internet.
Quain, John R. Searching safari: all you need to know about portals, engines and bots . Article covering beginning aspects of internet searching.
Wildstrom, Stephen H. Search engines with smarts. Author
discusses new specialized search tools for the Internet
that help users find the information they want.
Robison, Lori. Expand your Web search. Advice is provided on using metasearch engines.
Gladstone, Darren. Web outstrips search engines' reach. Discussion on the challenge search engines face with the ever growing WWW.
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Copyright Adrienne Arthur. Last Updated May 6, 1999.