Libraries use classification systems to organize the books on the shelves. A classification system uses letters and numbers (call numbers) to arrange the books so that books on the same topic are together. Academic libraries use the Library of Congress Classification System (LC), which has 21 classes and over 225 subclasses, represented by letters.
Familiarize yourself with these classes and it will help you to find books and shelve more quickly.
Read call numbers line by line.
- Read the first line in alphabetical order
- Read the second line as a whole number
- Read the third line alphabetically first, then as a decimal, eg: .C65 = .65 .C724 = .724
- Some call numbers have more than one letter-number line
- The last line is the year the book was published. Read in chronological order.
- Remember: NEVER GUESS. If you're not sure what a call number says, ask us.
![Ten Library of Congress call numbers in order on a shelf. On the first line, 'LA' before 'LB'. On the second line, '2327' before '2328'. On the combination letter number line 'B' before 'C'. For the numbers after the letter on the combination line, '.55' before '.554' and '.554' before '.63'. For the last line, '1987' before '1991'.](https://www.usg.edu/galileo/skills/unit03/images/03_04h_shelfcallnumber.jpg)
Image taken from The Online Library Learning Center website, a project of the Board of Regents of the University System of Georgia