Boolean Operators are used in keyword searches to link together two or more terms. The most commonly-used operators are: AND and OR.
AND narrows a search; you get fewer records because each concept must be present in the records found — here the area in blue below. Use AND to combine different concepts in one search.
OR broadens a search; you get more records because OR includes each of the concepts separately, as well as the concepts when found together. OR is often used to link together related concepts.
Watch the brief video below for a more detailed description of how Boolean Operators are used to connect and define the relationship between your search terms using AND, OR, or NOT.