Long Island University C.W. Post Campus
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Reference

Library vs. Web

Untangling The Web

Evaluating Internet Resources

Checklists for Evaluating Information

Anatomy of a URL

More Search Engines

Contact Reference

Library Homepage


Boolean Basics for Search Engines


The Reference Department has a website that provides a wealth of information to researchers, students and net surfers. Check us out at: http://www.liu.edu/cwis/cwp/library/ref/refhome.htm

Click on the Virtual Reference Collection for links to many Search Engines that will help you find information by name or subject on the Web. But rummaging through the Web can take forever, unless you know how to refine your search by using special commands. Below are explanations of some of these commands. Some search engines alter these commands slightly, so click on their help buttons for instructions first.

BOOLEAN LOGIC was developed by a 19th century English mathematician, George Boole. It allows you to combine topics to make your search more specific or broader. The most common Boolean operators are AND, OR, NEAR, and NOT.

AND (e.g., teenage AND pregnancy) will look for only those sites containing BOTH topics, and creates a narrower and more specific search than OR.

OR (e.g., teenage OR pregnancy) will look for all sites containing EITHER teenage or pregnancy, but not necessarily both. Therefore it is a much broader search. You would more likely use OR to include various terms for a given topic. For example, teenage OR adolescent will cover sites that use either term for that age group.

NEAR (e.g., teenage NEAR pregnancy) will find those keywords in proximity to each other. (Check the Help screens for each search engine to determine usage.)

NOT (e.g., pregnancy NOT abortion) will look for all sites relating to pregnancy but exclude all that mention Click abortion.

QUOTATION MARKS can be used in some search engines such as AltaVista to retrieve a particular phrase such as "teenage pregnancy" or "Long Island University". Other search engines will simply treat the words as separate terms, and look for sites that include any of the terms or all of them.

WILDCARDS are a form of truncation. By inserting an asterisk (*), called a "wildcard," after or in the middle of a word you will retrieve plurals, suffixes, and alternate spellings. For example, cultur* will retrieve culture, cultures, or cultural. Wom*n will find woman or women.

PLUS AND MINUS SIGNS are similar to AND and NOT. A plus sign (+) placed before a term will retrieve only documents containing that term. A minus sign (-) placed before a term will exclude it from the search: e.g., teenage + pregnancy -abortion

NESTED SEARCHES are groupings within parentheses that incorporate more terms into a search request, and can make your search more precise or more thorough. For example: (teenage or adolescent) AND (pregnancy or Planned Parenthood) AND smoking. While some search engines allow you to form such complicated search requests, combining different Boolean operators should be done carefully.



Search Engine Strategies

The easiest way to search the World Wide Web is to use a search engine which is a sort of Internet gateway. Also called "spiders" or "crawlers", they locate websites on the Internet, catalog them, and create links to them. These engines scan millions of sites on the Web for keywords, phrases, subjects, titles, and names. There are more than 260 search engines already trolling the Web, and that number continues to grow. Below are a few of the most popular ones, and some tips on searching them. Additional ones are listed under Search Engines on the Virtual Reference Collection page.

ALTAVISTA (www.altavista.digital.com)
Fast and comprehensive, AltaVista (begun in 1995) is one of the largest search engines in terms of pages indexed. It covers the entire Web and Usenet (a collection of user groups within the Net). With over 30 million sites indexed, this search engine often retrieves an abundance of hits, but advanced searches are easily accomplished, and it supports phrase searching. It also prompts you to refine searches by requiring or excluding topics.

EXCITE (www.excite.com)
Launched in 1995, it offers the best of both worlds: powerful search engine and well-organized index. Excite helps you refine or expand your search by offering suggested terms and asking if you wish more documents like the ones it found. It also has a list of reviewed sites, a Newstracker to help you follow your personal news interests, a chat room, and a City.net feature, with guides to more than 4,000 destinations around the world. Since Excite indexes over 50 million sites, you may get more hits than you want unless you narrow your search.

HOTBOT (www.hotbot.com)
One of the most comprehensive search engines, Hotbot was launched in 1996 by Wired Magazine. It uses pull-down windows for Boolean options and for date, location, and other refinements. You can also specify media, selecting pages with sound, still and video. Covering over 54 million sites, Hotbot has useful search aids and advanced search features. Like Excite, Lycos, AltaVista and Yahoo, it offers free email accounts.

LYCOS (www.lycos.com)
Lycos (Latin for "wolf spider") is one of the oldest search engines, running since 1994. The 66 million sites indexed can be searched for text, pictures, or audio, with results viewed in a choice of formats. It also has preselected subject categories. Clear help pages guide you through simple and customized searches. Lycos also offers a number of features, such as City Guide, Companies Online, News Headlines, and its selection of the top 5% of the most popular websites. Its own gallery of 80,000 pictures, with access to 18 million web images makes this a good site for retrieving graphics. Perhaps because of its size, Lycos tends to be slow to access and retrieve search results, but its versatility is impressive.

INFOSEEK (www.infoseek.com)
One of the smaller engines, it searches 500,00 web pages but provides accurate and relevant hits and designates Select Sites with a mark. Under Search Tips you can find simple ways to achieve optimum results. Use capitals for proper nouns. The Extra Search Precision feature (E.S.P.) will give better results with one or two word searches. As in AltaVista, phrase searching is available using quotation marks. Preselected categories on the main screen allow you to narrow your search. [Note: this site has been taken over by go.com]

GOOGLE! (www.google.com)
This new kid on the block improves the relevancy of your search results by considering the links to a site, and it also gives you excerpts of the matching text.

NORTHERN LIGHT (www.nlsearch.com)
Besides indexing web pages, it also classifies documents by topic. Also "Special Collection" documents from materials not generally available on the Web can be searched for a fee. You can use boolean operators, parenthetical expressions, phrase searching, and truncation symbols: Use * for multiple characters and % for only one.



Directories
Directories are created and organized by humans, and sites must be submitted and then categorized. Sometimes you can achieve better results using directories over search engines. One of the oldest and most popular website directories is Yahoo!

YAHOO! (www.yahoo.com)
More a directory than a true search engine, Yahoo! may be the easiest place to begin your search because of the preselected subject categories. Additional features include: Maps, People Search, a telephone and e-mail directory, and the latest news, sports, and stock quotes. Weekly Picks offers the latest additions to the Yahoo index of 370,000 sites. If Yahoo can't find anything in its own database, it will automatically direct you to its mammoth search engine partner, Inktomi which indexes 110 million Web pages.

MINING COMPANY (www.miningco.com)
This directory holds a network of sites selected and indexed by subject specialists or "Guides". Each "GuideSite" treats a single topic with feature articles, links, discussions, and site reviews. [Note: this site has been taken over by about.com]



Metasearch Engines
Unlike true search engines, metacrawlers don't search the web themselves; they compile results from other search engines and present them to you. The following are some examples. You might want to try one of these first to see which search engines will find the best information on your topic.

DOGPILE (www.dogpile.com)
This metacrawler covers 13 Web search engines, more than two dozen on-line news services or other types of sources, and sorts the results by the search engine that found them. It's a good starting point to see which one will retrieve the most.

METACRAWLER (www.metacrawler.com)
This metasearch site compiles the results from Yahoo, Excite and five other search engines. It is a good way to get a quick view of what's out there, but it is difficult to refine searches.

SEARCH ENGINE WATCH (www.searchenginewatch.com)
Try this site for the latest information on many search engines and directories.



Final Tips
Most search engines provide some basic and advanced search tips. Some let you refine your search as you go along, by prompting you with suggested terms, or by allowing you to add your own. Always check each search engine's Help screens for specific instructions for that system.

Remember that search engines vary in their coverage, their features, and their mechanisms for choosing the most relevant sites for your topic. Try several to get the best results. Also keep in mind that search engines are always changing, and new ones are being added. Experiment to find the ones that work best for you.

For more information or further instruction in the use of these search engines or other web-based resources, come to the Reference Department.

Jackie Elsas, elsas@liu.edu
Mara Rosenthal, mrosenth@liu.edu
Updated 07/01 by MKBB

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