Boolean operators are used to combine concepts or ideas when searching. The three Boolean operators you will use in searching are AND, OR, and occasionally, NOT. The operator you select will determine if the number of results you retrieve is increased or decreased. In most searches you will use a combination of these operators in order to narrow or broaden your results as needed.
Use AND in between words in a search to:
EXAMPLE: Dogs AND Cats
Searches for cats AND dogs will retrieve articles that contain both the word "cats" and the word "dogs." If an article only contains the word "cats" but not the word "dogs", that article will not be retrieved.
Use OR in a search to:
EXAMPLE: Dogs OR Cats
Searches for cats OR dogs will retrieve all the articles that contain the word "cats", the word "dogs", or both. You can also add more search terms into the mix, with the understanding that this will further expand your search.
Use NOT in a search to:
EXAMPLE: Cats NOT Dogs
Searches for cats NOT dogs will retrieve all the articles that contain the word "cats", but excludes from that list anything that uses the word "dogs." You have to be very careful when using this operator, as it will severely restrict your results and you may miss something important. An example of when to use NOT might be when you're looking for articles about dolphins (the animal) and you keep getting results with Dolphins (the Miami football team) You could do a search like, dolphins NOT football.