• Operators determine how your search terms are combined in the search.
• They are sometimes called BOOLEAN operators (named after George Boole, a mathematician).
• The three main operators are AND, OR, and NOT. It's best to type them in using capital letters.

Using the AND operator

• When you search in a database, you might get too many results. 
• If you add extra search terms, and combine them with AND, you will get only results that contain both or all of the terms.
• This is a way of making your search more specific (narrower), and getting fewer results.

Using the OR operator

• Sometimes you might not get enough results.
• If you add extra search terms, and combine them with OR, you will get results that contain one or other (or both) of your search terms.
• This is a way of ensuring that you search for all terms that might be used in the literature. It makes your search less specific (broader), and you should get more results.

Using the NOT operator

• Sometimes you might wish to get results that exclude certain terms.
• If you add these terms with the NOT operator, you will exclude results that have those terms.
• This is a way of making your search more specific (narrower), and getting fewer results.
• NOTE: it might be better to search for what you do want, rather than what you do not want.

Example:  government NOT state

Nesting

• If you use different operators in the same search, you must use either round brackets or separate search lines. This is important to control the way the operators are applied in the search.