Boolean operators (AND, OR, NOT) allow you to refine and define your search statement . For example you may need to reduce the number of hits or titles that you retrieved. On the other hand, you may want to expand your statement by adding other terms to get more information. Sometimes you might find it necessary to exclude a specific term from your findings. Boolean operators permit you to manipulate your search in order to achieve some of these results.
Advanced Boolean techniques are used to manipulate your search statement by adding or subtracting terms, in order to arrive at the most precise information that you need. In the Basic Searching module of this tutorial, you learned that you use AND to narrow or decrease the number of results if you have retrieved too many titles. Remember that when you type a statement such as: gun? AND school? you in effect are requesting that both terms be found in all of your hits.(Note the use of the truncation symbol ? in the search statement. We will discuss this more later in this unit) Unit 3: 2 of 10