Boolean Operators

When you search with a keyword, the computer system matches it exactly against the indexed records. Search results are improved if you use the most specific words as your keywords e.g. voice recognition rather than simply technology. Keywords can be combined with Boolean operators: AND, OR, and NOT (sometimes AND NOT). Many search engines use the '+' symbol to represent AND; the '-' symbol to represent NOT.

'Lunar AND Eclipse' makes searches smaller
by limiting the matching records.

'Lunar OR Moon' makes searches bigger
by including all matching records.
'Lunar NOT Solar' makes searches smaller
by excluding some matching records.

Roberta Tipton and Ka-Neng Au, 18 Jan 2002