More about OR

This Venn diagram illustrates the use of the Boolean operator OR -- the colored area represents the result of the Boolean operation.

In this case, two concepts were combined using the Boolean OR and the result is a large set containing one or both of the terms.

And here's how the search strategy would look using Ovid MEDLINE:

1. coffee (4770 records)
2. caffeine (14310 records)
3. 1 or 2 (17991 records)

FYI:
Multiple OR operators can be used to combine more than two terms.
OR is most frequently used to combine synonyms.