Our library uses the Dewey Decimal System to organize many of our books. Melvil Dewey created this system a long time ago.
Fun Fact: We have the everyone readers and fiction books in separate sections, though they could also be put in the Dewey Decimal System!
The Dewey Decimal System is a little bit tricky until you get the hang of it. Books are in order by the number first, and then alphabetically by the author's last name after that. If several books have the same number, like in the ghost books section for example, once those are grouped together with the number you look at the letters next.