Like most university libraries, ODU Libraries use the Library of Congress (LC) Classification System, in which letters and numbers are assigned to each item.

If you were looking for a book about serial killers, for example, you may find one with the LC call number: HV6245 .N49 2000 HV = Social pathology. Social and public welfare. Criminology HV 6245 = Collective biography of criminal classes .N29 = author last name is Newton 2000 = publication date	HV 6245 .N49 2000

Catalogers assign subject headings to each item based on the Library of Congress Subject Heading list. Hopefully you've already learned how subject headings are different from keywords.

Knowing how the Library of Congress system works can be useful, especially when using print reference materials in the library. You can go to a particular call number area in the reference stacks and find useful dictionaries, encyclopedias, handbooks, directories, etc.--all on the same subject. Likewise, when you are in the library general collection stacks, you will be able to browse and find books on the same topic.

The following Web site http://www.loc.gov/catdir/cpso/lcco/ gives a breakdown of the Library of Congress Classification System.