Nesting can help you formulate more complicated searches. By using parentheses to contain certain terms, you can fine-tune your search.
Let's say you want burgers with ketchup and either mustard or mayo. You could use nesting to construct your search like this:
This way you get all of the following possible combinations:
ketchup AND mustard
ketchup AND mayo
catsup AND mustard
catsup AND mayo
The lines below illustrate the different combinations:
Now, since you didn't exclude any other condiments, it's quite possible that you'll get burgers with all three--mustard, ketchup, and mayo. Either way, you've still expanded your search so that you get more relevant hits. Nesting, you see, can be quite useful.
Still confused? Maybe just craving a burger? Contact a librarian or consider enrolling in the library's credit course (LIR 1011--Introduction to Academic Research), where you can learn all about Boolean searching and other skills for effective research. You can also check out our LibGuide on Truncation, another very useful search technique.