Almost all search topics are complex, meaning that they have more than one part and those parts interact in particular ways. For instance, if you were interested in investigating the ways college students use the Internet in their dorms for recreational purposes, this topic has many components.
Not only does your topic have several parts, but those parts need to relate in particular ways.
In order to translate the ways in which the different parts of a topic relate, we use Boolean Operators to develop search strategies.