Subject Indices

Tutorial Directory

What is a Subject Index?

A subject index (also known as a subject directory, web directory or just a directory) is the online equivalent of an organized file cabinet. Subject Index information has been thoughtfully organized by human editors into top-level subject areas. Subdirectories of related information are created by professional editors. The selection, classification, and evaluating of information is done by human beings who are content area experts. Contrast this with general results developed by search engine robots and you will see that Subject Indexes are an efficient wa to find quality resources.

How does a Subject Index Work?

Subject indexes follow a file within a file strategy.Human editors organize information by subject categories and create a hypertext linked format that structures a path from general to specific information. Patrons can use menus to browse their way into more specific subject indexes. Descriptive topic headings are briefly described on a main page, allowing the user to understand the contents of a subject category without clicking into it. In most subject indexes, you can also key word search the entire directory or from within a subcategory. Using a keyword search in a subject index does not search the entire web; instead your search is focused on just the files compiled by the editors of the subject index. Some subject indexes provide cross-referencing between categories that broadens your search.

Potential drawbacks associated with a Subject Index include

  • Deprecated Indices The trend is toward automated search engines and away from manually staffed directories.
  • Infrequent Updates: The information in a subject index may not be reviewed and updated as frequently as the results retrieved from a search engine. Editors may not be able to stay on top of changes quickly simply because they are humans rather than robots.
  • Fewer Records: The number of records in a subject index database will be much smaller than the total number of pages available to a search engine. Humans add subject index records to the database. Search engines rely on robotic software that can index thousands of pages a minute.
  • Inconsistent Quality: Since human editors craft subject indexes, the quality of the information is tied to the editor's expertise and abilities. You should expect a variation in the quality of the resources.
  • Bias: When you depend on another person to select materials, the possibility of bias increases. This is particularly true in controversial subject areas such as the middle-east or presidential politics. One way to test the quality of information in a subject index is to browse a topic you are very familiar with and judge the quality of the links in the category.

When should I use a Subject Index?

A business woman leafs through files.
  • Use a subject index when you have a general idea of what you are looking for, but need to develop more specific information. You'll be able to narrow the focus of your idea quickly by browsing in the right subject category. Once you find the right subcategories, the selection of information will help you decide on what you are really looking for. (If you were to enter a supermarket to shop for salad ingredients, you wouldn't go to the soft drink section to browse for dressings and croutons.)
  • Use subject indexes when you're not sure what you are looking for, but would recognize it when you see it. If you have a broad topic in mind like popular culture, music, product information, current events subject indexes are a good place to start your search. By browsing a subject index created by a knowledgeable editor you become more familiar with the details of a subject and better able to focus on specifics.
  • Browsing a subject index will teach you the specialized vocabulary of a subject. This is an excellent way to find keywords and search phrases for a specific query on a search engine. Indeed, veteran searchers will first turn to reliable subject indexes to develop their key word strategies before they begin using search engines.

When should I use a Search Engine Instead of a Subject Index?

The more specific and limited your area of investigation, the better it will be to use a search engine. Subject indexes help you go from broad categories of information to more specific ones. Search engines allow you use queries to find highly specific information. If you already understand the unique vocabulary needed to form a good query you might be better off with a search engine. Additionally, if you need timely information a search engine is more likely to produce up to the minute results

What is the difference between a closed model and open model directory?

An editor works at a computer workstation.
  • Closed directories like Yahoo! and LookSmart hire professional editors with subject matter expertise to make the decisions about categories and information organization. There's likely to be less variation in quality in a closed directory system.
  • Volunteer editors produce open directories. The abilities and expertise of volunteer editors will vary widely. Some may be exceptionally qualified, others inconsistent. It is reasonable to expect that the quality of information in an open director will vary accordingly. The Open Directory Project uses volunteer editors. The ODP supplies subject indexes to Google, Teoma, Alltheweb, Hotbot, AOL, and Lycos.

Deprecated Subject Indexes

Many once-popular subject directories are now defunct, closed in favor of more robust search engines. For example:

  • Yahoo! (deprecated in 2014)
    Yahoo! is an acronym for Y et A nother H ierarchical O fficious O racle was one of the first and most popular subject indexes. Yahoo's subject index was divided into 14 main categories. Each of these categories was further divided into subcategories.
  • The Librarians' Index to the Internet (deprecated 2015)
    This site, subtitled Information You Can Trust, was a program of the State Library of California. The Librarians' Index to the Internet ( was a searchable, annotated subject directory of more than 11,000 Internet resources selected and evaluated by librarians.
  • The Open Directory Project (now archived)
    Also known as the ODP or DMOZ, this site was the premier open subject index on the net. At one time the Open Directory Project claimed to be "the largest human-edited directory on the Web." Major search engines like Google, Teoma, HotBot, and Lycos, contracted with the Open Directory Project to provide directory services. It still works but is much smaller than it once was.
  • (deprecated 2013)
    This site employed expert guides to develop and moderate information and interaction in 23 'channels'.

How Can I Find Highly Specific Subject Indexes?

There are still subject indexes available through the WWW and you can use any of the major search engines to find them. Many subject indexes are highly specialized and may just fit your individual needs. Use these terms as keywords: "subject index", "web directory", directory, and search with the powerful intitle: operator.

Example: grants intitle:"subject index"

Example: history lessons intitle:"subject directory"

Authored by Dennis O'Connor 2003-2004, updated 2020