Many databases and indexes assign controlled words, subject headings or descriptors to database records. This is done to improve access to information. For example, in an education database the phrase "elementary education" would be used as a subject heading/descriptor for all articles about kindergarten through grade six. Using the descriptor will retrieve references to articles on the topic, even if the phrase "elementary education" never appeared in the title or abstract of the articles.

Different databases may use different controlled vocabulary terms. For example, the following terms are used by these catalogs and databases:

 Use the following tips and techniques to improve your database searches:

• Use boolean logic (AND, OR) to combine terms that best describe your topic. Use alternate terms to expand your results.
• Carefully examine the descriptors or subject headings in relevant records to use in your next search.
• Do not use phrases like "the effect of television violence on children." Instead, combine keywords representing the individual concepts:

children AND violence AND television

• If you find too many sources, add another term to NARROW your search

children AND violence AND television AND effects

• If you don't find enough sources, use fewer terms to BROADEN your search
  • children AND television  or
  • child* AND (television or media)
    • This last example uses both truncation and nesting.

    Please feel free to ask librarians to assist you when you need to use more complex search statements to get the results you need. Each database may have different rules. You may need to try different combinations of different terms in each database to see what works.