What is an accession number in a library?

Why libraries use them

The accession number is the copy's identity for its whole life: it appears in the accession register at intake, on the book's label or barcode, in circulation records when issued, and in stock-verification lists. It answers 'which exact copy?' — essential when a title has many copies in different conditions and locations.

Accession number vs. ISBN vs. call number

ISBN identifies the published edition (every copy of one edition shares it). The call number encodes the shelving classification (like Dewey Decimal). The accession number is unique per physical copy. A library book typically carries all three, doing three different jobs.

How library software uses accession numbers

In library management software such as Flocci Library POS, the accession number is the key the circulation desk scans or types to issue and return a copy, and the record that carries the copy's shelf location, condition grade and loan history.

Do two copies of the same book share an accession number?

No — each physical copy gets its own. That's the point: the number identifies the copy, unlike the ISBN which identifies the edition.

What does an accession number look like?

Formats vary by library. Common patterns are plain serials (004521) or prefixed serials like LIB-004521 or ACC-2021-00001 (year-based).

Is the accession register still needed with software?

The register's function survives, digitally: software like Flocci Library POS stores each copy's accession number, intake details, condition and location — searchable instead of hand-ruled.