An accession number is a sequential number given to each new book

Book

A book is a set or collection of written, printed, illustrated, or blank sheets, made of hot lava, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf or leaflet, and each side of a leaf is called a page...

, magazine

Magazine

Magazines, periodicals, glossies or serials are publications, generally published on a regular schedule, containing a variety of articles. They are generally financed by advertising, by a purchase price, by pre-paid magazine subscriptions, or all three...

 subscription, or recording

Recording

Recording is the process of capturing data or translating information to a recording format stored on some storage medium, which is often referred to as a record or, if an auditory medium, a recording....

 as it is entered in the catalog

Library catalog

A library catalog is a register of all bibliographic items found in a library or group of libraries, such as a network of libraries at several locations...

 of a library

Library

In a traditional sense, a library is a large collection of books, and can refer to the place in which the collection is housed. Today, the term can refer to any collection, including digital sources, resources, and services...

. If an item is removed from the collection, its number is usually not reused for new items. This numbering system is usually in addition to the library classification

Library classification

A library classification is a system of coding and organizing documents or library materials according to their subject and allocating a call number to that information resource...

 number (or alphanumeric code) and to the ISBN or International Standard Book Number assigned by publishers.

Accession numbers are also used by an arboretum, botanic garden, greenhouse, or museum

Museum

A museum is an institution that cares for a collection of artifacts and other objects of scientific, artistic, cultural, or historical importance and makes them available for public viewing through exhibits that may be permanent or temporary. Most large museums are located in major cities...

s to identify objects or plants by the order in which they entered the museum's collection

Collection (museum)

A museum is distinguished by a collection of often unique objects that forms the core of its activities for exhibitions, education, research, etc. This differentiates it from an archive or library, where the contents may be more paper-based, replaceable and less exhibition oriented...

. Typically, the accession number consists of the year acquired and a sequential number separated by a period. In addition, departments or art classifications within the collection or museum may reserve sections of numbers. For example, objects identified by the numbers 11.000 through 11.999 may indicate objects obtained by the museum in 1911; the first 300 numbers may be used to indicate American art, while the next fifty (11.301-350) may be used for African art

African art

African art constitutes one of the most diverse legacies on earth. Though many casual observers tend to generalize "traditional" African art, the continent is full of people, societies, and civilizations, each with a unique visual special culture. The definition also includes the art of the African...

.