Boolean Operators are a set of commands that can be used in almost every search engine, database, or online catalog to provide more focus to a search. The most basic Boolean commands are AND and OR. In PubMed, you can use Boolean Operators to combine search terms, and narrow or broaden a set of results.
Narrow Results with AND
Use AND in a search to narrow your results. It tells the search engine to return results that contain ALL the search terms in a record.
adolescents AND depression
Note: Both the words adolescents and depression will be present in every record in the results.
Broaden Results with OR
Use OR in a search to broaden your results by connecting similar concepts (synonyms). It tells the search engine to return results that contain ANY of the search terms in a record.
adolescents OR youth OR teenagers
Use parentheses ( ) to keep concepts that are alike together, and to tell the database to look for search terms in the parentheses first. It is particularly important when you use the Boolean Operator “OR”.
(adolescents OR youth OR teenagers) AND depression
field tags tell the database where to search
[ti] = title
[tw] = textword (not full-text)
[tiab] = title/abstract
[mesh] = Medical Subject Heading
[au] = author
pharma* = pharma, pharmacy, pharmacist, pharmaceutical, etc.
quotations for phrase searching
“hand and foot melanoma”