- Operators allow search termsto be combined to make more precise queries. The operators are: OR: The conjunction operator 'OR' links two terms and finds documents including either one similar to a Union of sets. The symbol "||" can be used in replacement. AND: The intersection operator 'AND', used by default if you do not provide any operators, links two terms and finds documents including both of them. The symbol "&&" can be used in replacement. NOT: The operator 'NOT' excludes results which have the terms preceded by this operator. The symbol "!" can be used in replacement. This operator cannot be used with just one term, because it will give no results - its function is to remove items from a result set. + The term preceded by this operator must be present in the search result. - Results including the term preceded by this operator are excluded. () Parentheses group certain terms and operations. For example: "(John AND Smith) OR Jones" is not the same as "John AND (Smith OR Jones)".