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Before you begin searching, you first need a little understanding about how information is stored and accessed on the Web. There are basically three categories of information on the Web:
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The Free, Visible Web. This category includes all the publicly mounted Web pages. These pages are indexed by search engines. To find information from this category, use a good search engine or directory. |
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The Free, Invisible Web. This category includes the contents of sites that provide their articles or information free to users, but that content may be accessible only by going directly to the site. In other words, search engines cannot index it. Some magazines, newspapers, reference works, and other sites are in this category. Many databases such as legal, medical, and financial are here, too. To find information from this category, you must go to the appropriate database. |
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Paid Databases over the Web. This category includes commercial databases that libraries subscribe to, containing scholarly journals, newspapers, court cases and the like. Providers like Lexis-Nexis, UMI Proquest, Infotrac, JSTOR and others are in this group. To find information from this category, you must have access to the database (through password or an on-campus computer) and search on the database directly. |
Search tools fall into three main categories. (Note that a given search site may combine tools, since sites are in a constant state of change, merging, and partnering.)
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Search Engines. A search engine consists of the interface you use to type in a query, an index of Web sites that the query is matched with, and a software program (called a spider or bot) that goes out on the Web and gets new sites for the index. The bot crawls the Web at certain intervals, in order to index new material. When you use a search engine, you are asking it to look in its index to find matches with the words you have typed in. Some search engines index not only the World Wide Web, but also Usenet newsgroups. Many search engines are now becoming reference sites which contain much more than just search capability. They may also have news, weather, free software, picture indexes, ratings of web sites, and other features. There are several hundred search engines, but they fall into a handful of types: |
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Global. This type of engine, typified by Google, Fast Search, Northern Light, HotBot, AltaVista, and others, reads pages from all over the world in many languages. These engines may index more than a billion pages. |
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Regional. Some search engines are limited geographically. For example, only information on Web sites in Australia may be indexed. |
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Targeted. These search engines limit themselves to one subject, like biography, medicine, graphics, art, fishing, and so forth. |
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Reference. These provide information from a set of reference works, such as an encyclopedia. Britannica, Bartleby and xrefer are examples. |
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Directories. Directories are categorized lists of sites picked out by human editors. Directory databases are therefore much smaller than those of search engines. However, the fact that the sites are hand picked often means that you will find very high quality sites or articles in the results. Example directories are Yahoo, Look Smart, and Snap. |
NOTE: This page and its direct links are adaptations of pages created
by
Robert Harris
Vanguard University of Southern California
original
text can be found here
