What is Boolean Logic?
Boolean logic defines logical relationships between terms in a search. The boolean search operators are AND, OR, NOT. Enter these terms in ALL CAPS in the databases because many search engines, although not all, are case sensitive for these concepts.
AND
By using AND in your literature search, you are telling the database to bring back search results in which both search terms occur.
For example, if you are running a searching for "gait training for Parkinson disease" you may want to write it out as "gait training AND Parkinson Disease". The search engine will recognize that you are looking for both concepts together.
OR
By using OR, you are having the database search for either of the items you are looking for. This broadens your search results.
For example, if you run a search for "gait training AND Parkinson disease" you will potentially miss out on articles that deal with "gait rehabilitation". However, using OR you can run a search that uses both concepts. For example, "(gait training OR gait rehabilitation) AND Parkinson disease". Running a search with OR increases your search results, but also increases your chances of finding more relevant articles