Once you have identified key concepts in your search, you will need to combine them. Boolean operators AND, OR, and NOT can be used in most databases and many search engines to combine your search terms depending on whether you want to broaden or narrow your search.

AND - finds all records which include both words/phrases bullying and teenagers   Use AND to narrow your results.

OR - finds all records which include either or both words/phrases (use with synonyms) teenagers or adolescents   Use OR to broaden your results.

You may also combine AND and OR: bullying and teenagers or adolescents

Many search systems (usually in Advanced Search mode) provide boxes to separate your search terms:

But, you can combine your terms on one line as well. It's up to you.

NOTE: When using AND and OR in the same statement, use parentheses to put terms into logical groupings (as in this Basic Search box).

The database combines the terms in the parentheses first, and then combines those with the rest of the search terms.  Without the parentheses, the computer may interpret your statement in an erroneous way:

bullying and adolescents or teenagers

There's still another Boolean Operator we haven't mentioned -- NOT

NOT finds records which include one term but not the other
Use NOT with caution! You may exclude valuable records that include both words.

teenagers not children -- this would exclude records that include teenagers and children