George Boole, 1815 - 1864
George Boole was an English mathematician who helped establish the field of mathematics called symbolic logic. Boolean logic uses words called operators. The three main operators are: AND, OR and NOT.
Databases use Boolean logic to locate only those items that match your search. The blue areas in the following diagrams represent the results you would receive from doing a search using the Boolean operators AND or OR in the same database:
using OR retrieves a large number of items: