ISSN

An ISSN (International Standard Serial Number) is an eight-digit identifier, defined by ISO 3297, assigned to a continuing resource’s title — a journal, magazine, newspaper, or other periodical published on an ongoing basis, whether print or online. The critical distinction for research-administration purposes: an ISSN identifies the serial title, not any individual article, issue, or volume published within it. That article-level identification is the job of a DOI, not an ISSN.

What Makes Something an ISSN (Operational Definition)

A valid ISSN has a fixed, checkable structure: two groups of four digits separated by a hyphen (NNNN-NNNC), where the final character is a check digit computed with a modulus-11 algorithm across the preceding seven digits — that check digit may itself be the letter X when the calculation resolves to 10, to keep it a single character. This is the same check-digit design principle used by ISBN, though the two are separate, non-interchangeable schemes administered by different agencies.

A worked example ISO itself uses to illustrate the calculation: Hearing Research, ISSN 0378-5955, where the final digit (5) is the computed check digit. A widely recognized second example: Nature carries ISSN 0028-0836 for its print edition — that ISSN identifies the journal Nature as a title. It does not, and cannot, distinguish one Nature article from another; any individual Nature article instead carries its own DOI (for example, https://doi.org/10.1038/nature14539), issued at the article level by a DOI Registration Agency such as Crossref.

Who Assigns an ISSN

ISSN assignment is coordinated internationally but executed nationally. The ISSN International Centre (also known by its French acronym CIEPS), an intergovernmental organization created in Paris on 21 January 1976 under a UNESCO-France agreement, maintains the global ISSN Register and the ISSN International Portal, and assigns ISSNs directly only for countries without their own national Centre. In most countries — including the United States, where the US ISSN Center is based at the Library of Congress — a national ISSN Centre handles the actual registration: a publisher supplies the title, publisher name and address, and evidence the publication genuinely exists (a URL and proof of publisher identity for an online serial; cover, title-page, or early-issue documentation for a print one). Registration is free through the national Centre’s intake system.

ISSN vs. DOI

These two identifiers operate at different levels of the same publication and are not interchangeable:

• ISSN identifies the serial title as a continuing whole — one ISSN (per print or online format) for the entire run of a journal, however many volumes or articles it eventually publishes.
• DOI identifies an individual object — typically a single article, but also a dataset, preprint, or other discrete output — with a new DOI minted for each one.

In practice, a journal article’s citation metadata commonly carries both: the ISSN establishing which journal it appeared in, and the DOI resolving to that specific article. Neither substitutes for the other, and a search or citation tool that only accepts one will not find records indexed under the other.

ISSN vs. ISBN

ISSN and ISBN are both eight-to-thirteen-digit ISO-defined identifiers with a check-digit design, which is where the resemblance ends. An ISBN (International Standard Book Number), administered by the International ISBN Agency — a separate body from the ISSN International Centre — identifies a monograph: a single, stand-alone book or a specific edition of one. An ISSN identifies a continuing resource that is never “finished” the way a book edition is: a journal keeps the same ISSN across every issue and volume it ever publishes. A book series that also functions as a continuing serial can, unusually, carry both an ISSN (for the series as a whole) and individual ISBNs (for each volume) — the two schemes are complementary in that edge case, not substitutes for each other.

ISSN-L: Linking Print and Online Editions

When the same title exists in more than one medium — typically a print edition and an online edition — each medium is assigned its own, distinct ISSN. To let library systems, citation databases, and discovery tools treat those as “the same title” for search and linking purposes, one of the two ISSNs (conventionally the print ISSN, where a print edition exists) is designated the ISSN-L (Linking ISSN), representing the title across all its registered formats.

What an ISSN Does Not Confer

Because ISSN registration only confirms that a title, publisher, and format genuinely exist, holding a valid ISSN is not evidence of any of the following, despite a common assumption to the contrary:

• Peer review. Magazines, trade newsletters, and non-peer-reviewed publications are assigned ISSNs on exactly the same basis as peer-reviewed academic journals.
• DOAJ inclusion or other legitimacy vetting. A predatory or low-quality journal can carry a perfectly valid ISSN; ISSN registration performs no editorial-quality check.
• Copyright or trademark protection. ISSN registration is a bibliographic identifier assignment, not an intellectual-property filing.
• Indexing in Scopus, Web of Science, PubMed, or any other database. Those are separate, independent indexing decisions each database makes on its own criteria.

Related CASRAI Terms

• DOI — the article/object-level persistent identifier that pairs with (and is often confused for) an ISSN.
• Academic Journal — covers the fuller set of markers (peer review, editorial board, aims and scope) that distinguish a scholarly journal from any other ISSN-bearing serial.
• URN — a broader persistent-identifier namespace family that ISSN itself can be expressed within (an ISSN can be represented as a URN, per IANA’s registered ‘issn’ URN namespace).

References

• ISO 3297, Information and documentation — International standard serial number (ISSN).
• ISSN International Centre, ‘What is an ISSN?’ and ISSN Portal documentation (issn.org / portal.issn.org).
• US ISSN Center, Library of Congress (loc.gov/issn).