A Boolean operator, in the context of search engines, is a conjunction used to filter results by combining or excluding specific words and terms in queries. Search operators, sometimes referred to as a search parameters, are characters or strings of characters – including words and phrases – that are used in a search engine query to narrow the focus of the search. Boolean operators are a common type.
Boolean operators and how they work:
AND is an operator that gathers only results containing both words typed immediately before and after the operator. Results with either term singularly will not be returned. In Google, the AND operator is implied by a space.
OR is an operator that returns results containing both the word typed both before and after the operator (as with AND) as well as results containing either word individually. The vertical slash - | - represents the same operation in some systems.
XOR (although, strictly speaking, not a conjunction) is an operator that allows results that contain either the word before the operator or the word typed after the operator but not results including both. XOR stands for exclusive OR.
NOT (AND NOT in some systems) is an operator that gathers results only containing the word typed before the operator and excluding results that include the work following the operator, even if they contain the first desired term. The Google search engine uses the minus sign placed before a word to exclude results containing it.