Most useful when you cannot seem to find keywords, a directory provides guideposts organized by a hierarchical structure to help you in your search. Web sites are stored within major categories, further subdivided by subcategories, which are further subdivided into topics. The technology behind the order in which relevant sites are delivered and ranked when a user submits a keyword search to a search engine is a closely held secret, much like the recipe to McDonald's secret sauce. Factors currently used to predict relevance can be divided into those based on factors relevant to the page and those based on factors external to the page. Some engines rank higher if the URL name has relevant keywords in it.
Many search engines have a simple mode and an advanced mode.
Knowing a few basic rules to the advanced mode can be very helpful to a visitor wishing to better define their search. Each search engine varies in their capabilities so it is wise to check the HELP or FAQ sections before beginning a search. You then realize that you really wanted to know about Richard Nixon's 1962 Campaign for Governor of California. This feature allows you to then refine your search. In addition to the search engine technology, metasearch engines and directories provide capabilities for visitors to find what they want on the web.