The library catalog gives you the information you will need to locate the book. On the example record below, there is a section titled Holdings. The information in this section includes the call number, the number of copies, which location within the library the book is shelved, and whether or not the book is checked out.
Call numbers are similar to a house address. It tells us where the book is shelved on the book shelves (also called “stacks.”) Each book in the library has a unique call number, so it is important to write down the entire number. Most college libraries use the Library of Congress call number system, which consists of letters and numbers.
The nice thing about call numbers is that they group books on similar topics together, so when you go to the book stacks, you may find other books on your topic nearby.