Old Dominion University Libraries

STARquest II: The Internet and the World Wide Web

6. Boolean Operators - AND, OR, NOT
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How do I look for more than one word?

Boolean operators are search commands that help to combine search terms and concepts. They are named for the British mathematician, Sir George Boole. Use Boolean operators to reduce or enlarge your search results.

Most commonly used operators

AND

Find pages containing all the specified words or phrases anywhere on the page.

Good for searching two simple terms. Both terms must be present in every document retrieved. Using AND will reduce the number of search results.


OR

Find pages containing at least one. but not necessarily all, of the specified words or phrases.

Good for searching synonyms and like terms.Will retrieve the largest amount of documents.


NOT

Excludes pages containing the specified word or phrase.

Will retrieve documents with only radiation present. No records are retrieved in which the word "nuclear" appears, even if the word "radiation" appears there too


( )

Operators can be used singly or combined. This is called nesting terms and shows which operation is performed first by the search engine software.

(computer OR computers OR computing) AND education

Using this method of nesting, we are assured that the OR terms are kept together as a logical unit.


*

The use of truncation or wildcards can expand your search and is helpful in making sure you retrieve all the variant spellings or endings of a word.

comput* AND education

Good when looking for terms with many possible endings. Some systems search word ending variants automatically. See the help screens for each of the search tools. Wildcards are used to take the place of characters within the word. Truncation is used at the end of the word.