Quality and reliability of the available information sources vary greatly and each document's standard should always be evaluated. The best known examle is maybe Yahoo a well organized subject tree with lots of information.
Searchers can connect to a search engine site and enter keywords to query the index.
These keywords should be chosen carefully, a specific term central to the subject filed or a combination of two or more such terms. The more specific the keyword, the better the search result. They contain a wealth of links to specific sites. The following represent only a few examples, for a more comprehensive listing see Dictionaries and Listings .