Although we call most search sites "search engines," not all of them are search engines, per se. You might be surprised to learn that Yahoo!, for example, is actually a search directory. So is The Mining Company. The difference between search engines and search directories lies in the way they find and categorize sites.

Search engines, such as Alta Vista, Excite, Infoseek and Lycos, rely on "spiders" or "bots" to troll the Web collecting information on new and updated sites. This information is put into the searchable database that you and I access when we enter a search query.

Search directories are created manually by people. This means that each of the sites in a search directory has been screened and categorized by a human being. In theory, search engines tend to provide a large quantity of results, while search directories yield more quality results. But anyone who has done a lot of research on the Web knows that you usually have to use several different search sites in order for your search to be comprehensive. With CNET's Comparative Search, you can type in a query to see how the most popular search sites handle the same search.

For information on how to get the most out of your searches, check out Search Engine Watch's chart of Power Search tips. Using Boolean terms, such as and and or, for example, can help you hone in on a particular topic. Using quotation marks will enable you to search for a specific phrase ("plate tectonics" or your own name, for example). Refer to CNET's Boolean Primer for details on this symbolic logic system developed by a 19th-century mathematician named George Boole.