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What's the Difference?

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 (exampleLibraries--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 an online thesaurus that you can browse to find the subject heading(s) that best match your topic.

ProQuest Thesaurus: Subject Search Example


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.


Adapted from:  University Library, University of Illinois at Ubana-Champaign