Boolean operators are named for English mathematician George Boole (1815 - 1864). Boolean operators are used to connect and define the relationship between the words in your search. The three operators most commonly used are:
|AND||All keywords listed must be in the citation, abstract, or article||LIMITS||nursing AND vaccine = both words present.|
|OR||Just one of the keywords needs to be in the citation, abstract, or article.||EXPANDS||dog OR canine = either the word dog or the word canine is present.|
|NOT||The word following the NOT will be excluded.||EXCLUDES||bee NOT spelling = insects but not the competitions|
Keep in mind the operators AND / OR are completely opposite to how we use them in everyday language:
There are symbols and punctuation that help further refine results:
These operators work in many commercial search engines, websites and databases.