AND - Commands a search engine to bring back both terms
OR - Commands a search engine to bring back either of the terms
NOT - Commands a search engine to ignore all results with a certain word.
Quick tip: in Google, use a minus sign (-) instead of NOT
Bring back exact search results. "Ohio State University" means only OSU, no Ohio University too.
What to learn more? Review these sections of Choosing and Using Sources
DO:
Do choose main topic words
Do use precise words
Do use Booleans!
Do use synonyms
DON'T
Don't use full sentences or sentence fragments
Don't be too vague when you are looking for something specific
Unless part of a proper name, don't include: A, The, An, etc.