Call Number
The alphanumeric code assigned to a book in a library that determines its physical location on the shelf — combining subject classification (Dewey or LC) with author and title information.
In context
The call number was 823.914 BECk — British fiction, 20th century, Beckett.
She copied the call number from the OPAC before going to the stacks, then couldn't read her own handwriting.
Home libraries rarely use call numbers, but the principle is the same: a code that tells you exactly where to look.
Did you know?
Most academic libraries use the Library of Congress Classification (LCC) system rather than Dewey, because LCC is more granular for academic subjects. The Library of Congress system uses letters and numbers (e.g., PR for English literature, QA for mathematics). Public libraries mostly use Dewey; academic libraries mostly use LC.
A call number is a book's address within a library — its precise location in a system that has given every volume a unique place to stand. Without call numbers, a library with hundreds of thousands of books would be unusable: a patron who found a record in the catalog would have no way to locate the physical book without searching shelf by shelf. The call number bridges the digital record and the physical object. It is the key that translates a search result into a shelf, a shelf into a book, a book into knowledge.
Call numbers in public libraries are almost always Dewey Decimal: a numeric subject code (like 823.914) followed by a cutter — a combination of the first few letters of the author's last name and sometimes a number, used to sort books with the same classification into alphabetical order by author. The cutter is why you find 823.914 BECk (Beckett) before 823.914 WOO (Woolf) on the same shelf: the classification is the same, the cutter alphabetizes within it. Academic libraries typically use the Library of Congress Classification instead: letters for broad subject areas (PR for English literature, QA for mathematics, HQ for family and gender studies) followed by more specific numbers and author cutters. LC is used in academic settings because it provides much finer granularity than Dewey for scholarly subjects.
The physical spine label — that small rectangular sticker on the bottom of a library book's spine — is the call number made visible in shelving order. It is the artifact of the catalog: the number from the database, printed and physically attached to the object it identifies. When a library recatalogs a book (reassigns it to a different classification), the old spine label is removed or covered and a new one applied. The label is, in a sense, a bookmark in the system: remove it and the book becomes a physical object unmoored from the intellectual address that told anyone where to find it.
Home libraries rarely need call numbers in the technical sense. An organized personal collection with a few thousand books can be navigated by shelving scheme (alphabetical, by genre, by subject, by size) without needing a coded address for each volume. The role the call number plays in a public library — connecting catalog record to physical location — can be fulfilled by knowing your own shelves well enough. But for very large personal collections, or for anyone applying a Dewey classification system at home, call numbers provide the same efficiency at home that they do in the stacks: a single string of characters tells you where to look and you don't have to hold the whole organizational scheme in your head.
The moment most readers encounter call numbers is in the transition between catalog and stacks: you search the OPAC, write down the call number, and go looking. That transition is one of the pleasures of physical library research — moving from the virtual index to the physical collection, navigating a system that has organized every book in relation to every other book on the same subject. The serendipity of the stacks depends on call numbers: you find what you were looking for, and on the shelf beside it is something you didn't know you needed.