Overview

The International Standard Serial Number (ISSN) is a standardized eight-digit code used to identify serial publications—periodicals and continuing resources—regardless of language or country of origin. It applies to titles issued in regular intervals and exists in both print and electronic forms. The ISSN system is defined by the international standard ISO 3297 and is coordinated through the global ISSN network.

Structure and check digit

An ISSN consists of eight characters displayed as two groups of four separated by a hyphen (for example, 1234-567X). The final character is a check digit that can be 0–9 or X (where X represents the value ten). The check digit is calculated using a modulus 11 algorithm to detect transcription errors and ensure integrity of the identifier.

Assignment and administration

Issuance of ISSNs is handled by national or regional ISSN centers operating within a coordinated international network. Publishers or libraries normally apply for an ISSN for a title; a separate ISSN may be issued for distinct media versions of the same title (commonly labeled p-ISSN for print and e-ISSN for electronic). An ISSN Linking ISSN (ISSN-L) may be assigned to group related versions of a serial under a single linking identifier for easier retrieval.

Uses and importance

ISSNs play a central role in library cataloging, subscription management, interlibrary loan, citation indexing, and electronic resource linking. They appear in metadata records, journal databases, and are often embedded in barcodes and publisher platforms to streamline distribution and discovery. By identifying a serial title rather than a specific issue, ISSNs help systems track titles across format changes and title merges.

  • ISSN vs ISBN: ISSN identifies continuing serials; the International Standard Book Number (ISBN) identifies monographs and individual book editions.
  • Multiple ISSNs: Different media or significant title changes can receive distinct ISSNs; ISSN-L links them.
  • Complementary systems: ISSNs are often carried in other identifier systems and metadata schemas to support digital object management and discovery services.

History and notable facts

The ISSN system was first established under the international standard ISO 3297 in 1975 to provide a consistent global method for identifying serial publications. Today the network of national centers and an international coordinating body maintain the registry, promote consistent application, and support integration of ISSNs into library and publishing workflows.