The Library of Congress call number is a unique identifier assigned to each book or other item in a library’s collection. It is composed of several parts that indicate the item’s subject, location, and other information.
Letters. The first part of the call number is one or more letters, which indicate the item’s subject area. These letters are called the “classification” or “class” number, and there are twenty-one main classes, each with its own range of letters.
Numbers. Following the letters are one or more numbers, which indicate the item’s specific subject within the broader subject area indicated by the letters. These numbers are called the “subclass” or “subclassification” number.
Decimal point. After the subclassification number, there is a decimal point, which separates it from the next part of the call number.
More numbers. Following the decimal point are one or more numbers, which indicate the specific item within the subclassification. These numbers are called the “book” or “item” number.
Cutter number. Some call numbers may also include a “Cutter” number, which is a series of letters and numbers that help identify the author or title of the item.
Additional information. The call number may also include additional information such as volume number, edition, or year of publication.
By understanding the different parts of a Library of Congress call number, you can locate items more easily within a library’s collection.