Every item has a unique call number, much like every house in a city has its own address. A call number places an item either in its subject area or in an alphabetical order.
Libraries use different types of numbering systems to classify their holdings.
A library's holdings are the materials and items owned by the library such as books, magazines, journals, video and audio cassettes, etc. The call number is usually printed on a white label and placed either on the spine or on the cover of the item. You may locate call numbers in the library's online catalog. You must copy the entire call number in order to locate the item. Every book has a unique call number, much like every house in a city has its own address.