Boolean Operators are three words (AND, OR, NOT) that combine keywords into search strings. AND will narrow a search, OR will broaden a search, and NOT will narrow a search by excluding a keyword.
Examples:
vegetarian AND "animal rights"
vegetarian OR vegan
vegan NOT pescatarian
Quotation Marks can be used to search for exact phrases. You do not have to put quotation marks around one word or search strings.
Example: "animal rights"