menu

Boolean Searching

Boolean searching is simply a way of combining words and phrases when searching library catalogs and research databases. You can make your searches more focused and effective by stringing words and phrases together using these three Boolean operators: AND, OR, NOT

The diagrams will help to illustrate how the different operators work. For instance, the diagram below represents documents that mention alzheimers and exercise. The yellow region represents documents that mention alzheimers and not exercise. The blue region represents documents that mention exercise and not alzheimers. The green region represents documents that mention both exercise and alzheimers.

venn diagram

AND requires that both words or phrases are included in the search results.
Example: alzheimers AND exercise
Search results will include only records containing both the words alzheimers and exercise.
The diagram below illustrates how using the AND operator gives you fewer results. Of all the literature that mentions alzheimers and all the literature that mentions exercise, you want only the literature that mentions both alzheimers and exercise, represented by the green area.

venn diagram illustrating AND operator

OR requires that either of the words or phrases are included in the search results. OR is frequently used with synonyms.
Example: alzheimers OR dementia
Search results will include records containing the word alzheimers or the word dementia or both.
The diagram below illustrates how using the OR operator gives you more results. Of all the literature that mentions alzheimers and all the literature that mentions dementia, you want the literature that mentions alzheimers or dementia or both, represented by the yellow, green, and blue areas.

venn diagram illustrating OR operator

NOT requires that one of the words or phrases not be included in the search results.
Example: alzheimers NOT exercise
Search results will include only records containing the word alzheimers but not the word exercise.
The diagram below illustrates how using the NOT operator gives you fewer results and helps you to focus a search. You would use NOT if you were interested in all the literature that mentions alzheimers as long as it did not mention exercise, too. This search is represented by the yellow area, below.

venn diagram illustrating NOT operator

Nested Boolean searching is a more complex way of using boolean operators which uses parentheses to isolate concepts.
Example: (alzheimers or dementia) and (exercise or fitness)
Search results will include records that mention either alzheimers or dementia and either exercise or fitness. For example, this search might include a document that mentions alzheimers and exercise, another document that mentions dementia and exercise, another document that mentions alzheimers and fitness, etc.

HATCH LIBRARY 539 Longmeadow St, Longmeadow, MA 01106  •  (413) 565-1376  • 
Questions or comments about our web site? Let us know

Last updated: 10/07/13

Website By Gravity Switch