Databases use controlled vocabulary to index or tag articles and books. Often referred to as Subject Headings, these terms describe the main topics or concepts presented in the article or book.
For example in Sociological Abstracts (ProQuest) any article about teenagers, young adults, juveniles, youth, etc., will be tagged with the Subject Heading Adolescents.
Some databases have tools to help you find the controlled vocabulary terms. These terms usually include definitions. For example -->
- Thesaurus in ProQuest databases.
- MeSH (Medical Subject Headings) in PubMed.