Boolean operators--OR, AND, NOT--are used between search terms to combine concepts in a more precise way than is possible with keyword searching. See also Combining Terms in the Library Catalog (CLIC) for additional explanation.
The AND operator narrows a search, retrieving only records containing both term(s). AND is used to narrow a topic to a specific aspect.
Example: anorexia AND "college students"
The OR operator broadens a search, retrieving records that contain either term, but not necessarily both. It is used to combine synonyms or related concepts.
Example: anorexia OR bulimia
The NOT operator also narrows a search by removing all records that contain a particular word or phrase.
Example: anorexia NOT bulimia
The NOT operator is rarely used. It often screens out useful records.