How do LC Call Numbers correspond to subjects?
Answer:
The numbers you see on the spine of library books represent the US Library of Congress (LC, in library-speak) Classification System. Most academic/research libraries in the US use this system to determine the order of shelved items so that materials on the same topic can be browsed together by a library user.
An overview of the system can be found online at Library of Congress Classification Outline. You will note that each major heading (letter of the alphabet) is further divided into sub-classes for greater precision. For example, Class Q = Science and comprises numerous sub-classes representing each scientific discipline: QA = Mathematics; QB = Astronomy; QC = Physics . . . QE = Geology; QR = Microbiology; and so on.
