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Directories

Unlike search engines, which are highly sophisticated computer programs, directories are hierarchical listings of topics and subtopics compiled by humans. Each topic in a directory points to one or more web pages.

Yahoo! was originally a directory, not a search engine. It now combines both functions. You can either begin searching at the Yahoo! directory page http://dir.yahoo.com/ or you can click on the Directory tab above the search box on the regular Yahoo! search page.

The largest directory source now on the Web is the Open Directory Project (ODP). It is completely non-commercial and relies on tens of thousands of volunteers around the world who find the best content within their areas of expertise and organize it for the directory. So far 4 million pages have been indexed.

ODP is the closest we have to a comprehensive catalog of the best of the Internet. It sometimes is so busy that it cannot process your search. However, ODP feeds data to Google, Netscape, AOL and hundreds of other search engines. Thus, when you search the directories of these search engines, you are probably getting about the same results as if you had gone to the ODP website directly.

A third Web directory is Looksmart. It is smaller tha ODP and also includes paid listings. However, it also has a comprehensive database of millions of full-text articles from magazine and journals.

When to use a directory

When you have a general idea of the subject you're searching, but you're not familiar with the depth or breadth of the subject, a directory is a good place to start. For example, if you're interested in learning about different business-related newspapers but you don't know their names, you can use a Web directory to get a list of such publications.

Databases

Databases are organized collections of articles, names, and all sorts of other information. When you search a database you specify certain parameters, with the results showing only those items that match your parameters (e.g., all names beginning with the letter M; juvenile crime data in Florida from 1980 to 1990.)

There are thousands and thousands of databases on the Internet, many of which are not visible to your typical search engine. These are part of the "Deep Web." Google and some other search engines can sometimes find databases, but you may have better luck using one of the web directories or a Deep Web search engine.

Database search is usually a 2-step (at least) process. First you have to find the appropriate database. Then you have to search within that database. Google and other search engines can sometimes find certain documents just from a general search. However the information does not always exist in a document. Sometimes it doesn't exist until you ask for it: e.g., the current cost of a flight from City A to City B for 5 adults.


When to use a database

When you are searching for statistics, lists of names (e.g., psychologists or other professionals within a certain zip code), schedules, or any sort of collection or anthology of documents or other data, you will have more success drilling down through a specific database than by using a general-purpose search engine.