Tutorials & Guides : Boolean Operators
Boolean operators were developed by George Boole, a 19th century English mathematician.
If use these three little words appropriately your online searches will be both faster and more precise. You will find the most relevant information on your first or second search, without having to scan through pages and pages of useless hits.
How to use:
Use
AND to narrow your search. This search will look for documents that have both cats and dogs present.
Use OR to broaden your search. This search will look for documents that have either cats or dogs present.
Use NOT to narrow your search. This search will exclude documents that contain dogs. Use
NOT carefully. Notice the white space where the two concepts overlap. You may be eliminating documents that might be useful to you. In this case, you lose articles with the main topic of cats, but just happen to mention dogs.
NOT is most helpful when trying to distinguish between very different concepts that happen to have the same keywords. For example, a search for “depression NOT economics” will narrow your search to records that discuss the psychological condition and eliminate the unneeded hits about an economic slowdown.
More questions? Ask a librarian!