Actually, the workings of search engines such as Google, Teoma, All the Web, and AltaVista (just to name a few) is proprietary. But we can discern from experience some generalities:

• Some search engines attempt to be comprehensive, while others are selective. Google is an example of a comprehensive engine; it attempts to index everything it can. Yahoo, on the other hand, is best thought of as a directory.
• Search engines can generally only index static Web pages (pages that actually exist on servers, and that have extensions such as .HTML, .TXT, and sometimes .PDF. Be aware that most of the available Web information is hidden from search engines.
• Search engines vary in the frequency with which they index particular Web sites. Some sites (such as CNN or the U.S. Census Bureau) are probably indexed several times per day by the major search engines. Other sites (personal Web sites, for example) may only be indexed semi-annually.

Phrase Searching

With Google, enclose phrases in "quotes". This forces adjacency and limits the results. Ex.: "joint committee on printing".

File Format Searching

Often it is helpful to limit your search to a specific file format such as Adobe Acrobat (PDF), Word (DOC), PowerPoint (PPT), Excel (XLS), etc. To do this, type filetype:[extension]. Ex.: digital divide and filetype:ppt.

Domain Searching

A powerful way to restrict search results is to limit by Internet domain. For example, you could restrict results to educational domains (.edu), to government domains (.gov), or to Canada (.ca). To do this in Google, add site:edu to your search to limit to US educational domains.

Another useful trick is to search a secondary-level domain. To search for information on Museum Studies on University of Denver sites, search like this in Google: site:du.edu museum studies.

This strategy is very effective when looking for authoritative information from known Web sites such as un.org. To search for information on "child soldiers" from the United Nations site, search Google like this: site:un.org child soldiers.