Boolean logic is considered to be a well known search strategy used in
search engines and in databases; it helps the user to narrow and broaden
his search to get accurate information.
AND:
is used to narrow the search and retrieve records containing all of the
terms (both words) mentioned in the search.
Example:
Library services AND Marketing.
OR: It broadens the search and retrieves results containing any (or both
)of the words mentioned in the search
Example: Management OR Administration.
NOT: Narrow the search and retrieve records that do not contain the term
following it.