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Keyword Searching vs. Subject Searching

Are you wondering which option to choose in the library catalog and databases? These search tips will help you to get relevant results from library databases and catalogs.

What's the difference?

Here are some key differences between keyword searching and subject searching:




Natural language words describing your topic. A good way to start your search.


Pre-defined "controlled vocabulary" words assigned to describe the content of each item in a database or catalog.

More flexible for searching. You can combine terms in any number of ways.


Less flexible. You must know the exact controlled vocabulary term or phrase.

Database looks for keywords anywhere in the record (title, author name, subject headings, etc.).


Database looks for subjects only in the subject heading or descriptor field, where the most relevant words appear.

Often yields too many or too few results.


If a subject heading search yields too many results, you can often select subheadings to focus on one aspect of the broader subject.

Often yields many irrelevant results.


Results are usually very relevant to the topic.


When you do a keyword search or an "any word anywhere" search in a library catalog or a database, you can type in words that describe your research topic in any order and retrieve records containing those search terms. A major disadvantage of a keyword search is that it does not take into account the meaning of the words used as search terms, so if a term has more than one meaning (such as "mouse" - computer hardware or rodent?), irrelevant records may be retrieved.

When you do a subject search or a descriptor search in a library catalog or database, only the subject headings or descriptors are searched for words that match your search terms. In library catalogs and databases, items are assigned subject headings as access points to assist users in locating the content. These subject headings might be subdivided with more information (example: Libraries--History--20th century) or include a parenthetical note to clarify the meaning (example: Mice (Computers)). Using subject headings ensures that all items about the same topic have consistent subject headings and so they can all be accessed with one search term. This saves you time! If you're looking for information about "death penalty" you don't have to search for every word that might be used to describe the death penalty (execution, electrocution, capital punishment, death row, etc.). Instead, you can check a list of subject headings in an index or a thesaurus and retrieve all items on the topic with just one search.

How can you find out which subject headings are used?

Knowing the right subject headings to use will help make your searching more precise, but how can you find the subject headings for your particular database?

Look to see if your database has a thesaurus that you can browse to find the subject heading(s) that best match your topic.

ERIC thesaurus

This example is from the ERIC database. When you open the database, you can click on the "Search Tools" tab, then the "Thesaurus" tab. In the thesaurus you can search for terms that come to mind for the topic you're interested in, and then see which subject headings are assigned to those ideas.

If you were doing research on high stakes testing in elementary schools you might want to find out what subject headings bring together all the materials available in this database on that subject. First, you'd look up high stakes testing and find the correct subject heading:

ERIC thesaurus search for High Stakes Tests

After searching for high stakes testing in the thesaurus, we see that phrase is not a subject heading, but "High Stakes Tests" is a subject heading used in ERIC. When you click on the link, you'll see a full entry for the term with broader terms, related terms, and sometimes narrower terms as well.

Thesaurus entry for High Stakes Tests

Broader, narrower, and related terms can be useful search phrases. In this particular case you might want to add "Achievement Tests" and "Standardized Tests" to your search because they address aspects of your research topic. Note these subject headings!

The second element of this research subject is elementary schools - you only want information on high stakes testing in elementary schools. When you look up elementary school in the thesaurus, you see the subject headings on this topic.

Search ERIC thesaurus for "elementary school"

Now you're ready to put the search together!

Constructing subject search with descriptors

Be sure to put all the related terms on one row. Select "Descriptors, DE=" from the drop-down list.

Results of search

If you have too many results, click on "Edit Search" at the top of the page and remove some of the descriptors.

Another method of finding subject headings on your topic is to start by doing a keyword search, using words or phrases describing your topic.

Keyword search in ERIC

With this search, you get many fewer results than with the descriptor search above. Browse through your results list and find relevant results.

Notice the Subject or Descriptor field in those relevant records and note the terms used. Keep a list of them to help you remember.

Results of keyword search

Redo your search using the subjects or descriptors you identify. Your results will be much more precise and comprehensive than those from your initial keyword search.