Search engines use specialized software to create their listings automatically. A "spider" (or crawler) "crawls" the web, for example, by visiting a web page periodically, reading it, and following the links. An index (or catalog) of the entire web is then compiled from the spider's search. The search software looks through the index to find matches to a user's search terms and ranks them in order of perceived relevance. The higher the number the more relevant that particular search engine thinks a "hit" is. The search service's idea of relevancy may or may not be relevant for your purposes. 

Meta "crawlers"  search a number of search engines at one time. 

WWW site creators may submit their sites for inclusion in a subject listing or a directory manager may find them. Companies can also pay to be included in search results. The search software looks for matches only from the chosen sites. The search software can only operate under the parameters set up by the programmer. They all work differently.

Majpr brpwsers allow you to search by just typing in keywords into the Web browser location "box."

Search tips:

Because there are so many URL's contained in a database, getting search results which are relevant may take some time and know-how. Because search engines work differently, using the same search words in different search services may get you different results. Each search service provides useful tips for searching its own database. Some search services are case sensitive; some let you use phrase; some rank relevancy of results (Search services or engines which have relevancy ranking means that the higher the number in the ranking, the more relevant the content).

Don't limit yourself to one search engine. Check the search engines for their specific ways to refine your search. Be prepared to revise your search. Compare results using different search services. Using synonyms sometimes helps. Search services and engines don't know what would be relevant to your particular search. Since companies can now pay to be included in searches, the "hits" might include entries that are there merely because the business paid to have their company appear in search results.  Sometimes you may get results that are relatively meaningless. Searching is by no means an exact science. But, like using a library database, the terms you plug in affect the results you get back.

Most major search engines also allow you to search for online forums, newsgroups, images, and other categories of information.

Don't just rely on the Internet for serious research. A significant amount of scholarly research has not reached the Internet or is protected from public access by "members only" subscriptions. Don't neglect your library databases for scholarly resources.

Google is a leader in search engines.  According to  John Markoff and G. Pascal Zachary, as of April 2003, Google "handles 200 million searches of the Web each day, a staggering one-third of the estimated daily total. Google, they say, handles " hundreds of thousands of queries simultaneously from all over the globe, each in less than half a second"( In Searching the Web, Google Finds Riches, N Y Times, 4/13/2003).

The Vivisimo search engine, developed by researchers at Carnegie Mellon University in Pittsburgh, uses an automatic document clustering technology.  According to  PR Newswire,  April 8, 2003, Vivisimo's "breakthrough clustering and meta-search products retrieve textual information from one or multiple sources and automatically organize[s] the combined results" into relevant folders." 

Most search engines allow you to use Boolean operators. 

What are Boolean Operators?

Boolean operators or words or symbols which help you create specific relationships among keywords or phrases "OR," "NOT," "AND," or "NEAR" commands. Often there is a separate box in the search service or engine in which to place your Boolean operators. Some search services do not use Boolean operators.