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Once you have identified the individual key words you need to think about how to fit them together. Some databases and search engines let you type in a whole sentence. Others require you to type in the key words only.

Combining words: The booleans

You can combine your search words and phrases. Although database search screens may look different, most of them work using the Boolean Operators (joining words) AND, OR and NOT. These are used to narrow or expand your search.

All words must be found in each result eg,
bariatric AND adolescents finds results with both topics.
Some databases will automatically join the words with AND without you typing AND between words eg Google Scholar, PubMed, Search Everything on the library homepage
Narrows your search. Less results.
The results of your search must contain at least one of the words eg,
obese OR obesity OR overweight will find results with any of these words.
OR is used to join or combine synonyms.
Broadens your search. OR = More
Results must not include a specific word. Can be useful to remove a concept from your search BUT use it with care. Some databases use AND NOTNarrows your search. Less results.

Google, Google Scholar and PubMed  - OR must be in CAPS.


When you combine search terms with AND this will

When you search for 'acetaminophen OR paracetamol' this will

When you search for 'honey AND wounds' this will

If you would like more information about the origins of Booleans, see Wikipedia on George Boole

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