Alta Vista is an example of a search engine. It uses computers to collect information on as many web sites as possible. This information is stored in a database. Here, we can search that database and retrieve a list of web sites that match our search query. Search directories such as Yahoo are useful when you are seeking general information, or if you want to browse what is available on the web.
Search engines are best to use when seeking specific information.
Search engines can help you find that needle in a haystack. You can use a search directory to see what is available. From Yahoo's opening screen, we can select U.S. States, which is part of the category Regional. The Washington Post's Metro Subway page. If we follow the links for Maps, we can find a terrific map of DC's Metro Subway system, courtesy of the Washington Post.