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Advanced Search Strategies: Boolean Search Guide: Home

Speaking the Database's Language: Boolean Search

Unlike internet search engines such as Google, our library databases do not understand natural language. To search within the databases, you must use something called Boolean Search. Boolean Search is made up of five operators that help to make your search results more precise and relevant:

1) Quotation Marks " " 

2) Truncation *

3) AND

4) OR with ()

5) NOT

Quotation marks tell the system that you would like to see the whole phrase, in the order in which the words appear.

For example, if you were doing a search for "screen time", and you didn't use quotes, the database would search for results that have the words screen and time individually. You will get results for resources for the words screen and time, as well as 'screen time', making your results list much longer and less relevant.

Without quotations, you get results for both the phrase 'screen time', but also results for 'time' and 'screen' separately. This means that you are guaranteed to see more irrelevant results, and have a larger number of results in total. 

Image of search without quotation marks, where search results are less relevant and precise.

When we use quotation marks, we bring down our total number of results from 4,483 to 2,332, by ensuring that we are only seeing resources with the term 'screen time' represented. 

Image of the search results for the term using quotation marks.


Adding an asterisk onto the end of a truncated word tells the system to search for multiple endings to that word.

For example, searching for child* would give you results for 'children' and 'childhood', as well as 'child'. 

Image of search results for children truncated as child*.

AND joins together two different words to communicate that you'd like them both represented in your search results.

For example, if you were doing a search for results on screen time and children, you would connect them with AND, to ensure that both concepts are represented in the results: "screen time" AND child*. 

Image of search results for "screen time" AND child*.

OR is used to connect two terms that are typically synonyms or are otherwise interchangeable in the context of the search. OR tells the system that you would like results for either or both terms. For example, if I was doing a search on the effects of screen time on children, and I wanted results for either children or adolescents, this is how I would structure my query: "screen time" AND (child* OR adolescents). 

Image of search results for "screen time" AND (child* OR adolescents)

Why do we use parentheses? 

Parentheses are used to bracket the OR terms because it tells the system that we'd like it to work with our structure, as opposed to defaulting left to right. If we did not bracket those terms with parentheses, the system would search for results for "screen time" AND child*, but then search for adolescents separately, so that you would be getting results for adolescents that had nothing to do with screen time. 

NOT is used when you want to exclude a keyword or term.

For example, if I wanted to search for the effects of screen time on children or adolescents, but did not want results related to obesity, I would structure my query: "screen time" AND (child* or adolescents) NOT obesity. This would eliminate results containing the word 'obesity'.

Image of search results for "screen time" AND (Child* OR adolescents) NOT obesity.