When you connect your search terms with the words "AND" or "OR" you are asking the database to combine your search terms in specific ways to narrow or broaden your search. These words are called Boolean Operators.
Parentheses can be used when searching as well. They function just like they do in algebra -- they say (Do this operation first) THEN do this operation. You can nest the AND and OR operators into them.
You can find further information about AND, OR, and parentheses in the tabs to the right.
Modified from Rachel Arteaga, Butte College
AND focuses or narrows a search. If you want to answer the question "What is the impact of advertising on smoking in adolescents?" you can combine all of your keywords with AND. Advertising AND smoking AND adolescents will return results have all three keywords in the article.
OR broadens or expands a search to find all the words connected with the operator. Remember that a keyword search only looks for the word you enter. OR lets you put in all possible keywords that might mean the same thing. For example, youth OR adolescents finds all the documents that have either word in them.
Parentheses function just like they do in algebra. They say "do this operation first, then do this operation. You can nest the AND and OR operators into them.
For example, (youth OR adolescents) AND smoking first finds documents that have either the words youth or adolescents in them. Then, from those results, looks for articles with the word smoking in them.
When you use the * (shift / 8 on the keyboard) you are asking the database to return all the words that begin with the same letters. For example, psych* will find results that include the terms psychology, psychiatry, psychologist, psychiatrist, psychiatric, etc.
Quotation marks create a phrase. A database will search all the words together in the order you entered them. For example, "Obsessive Compulsive Disorder" will find those words in that order and will NOT include an article titled Obsessive focus on profit results in disorder among company managers.