ISSN – Definition, Structure & How To Get One

The ISSN is a globally recognized identifier for serial publications. Within professional printing terms, it serves as a key reference point for cataloguing, distribution, and library systems. It ensures that journals, magazines, and other ongoing publications can be distinguished even when titles are similar or change over time. The system supports both print and digital formats.

Definition: ISSN

The ISSN (International Standard Serial Number) is an internationally standardized eight-digit code used for serial publications, such as journals, magazines, newspapers, and newsletters.

• Administered by the ISSN International Centre in Paris
• Supported by a network of 90+ national centers worldwide

Two formats:

1. p-ISSN ➜ identifies the print version
2. e-ISSN ➜ identifies the electronic version

It ensures that serial titles can be clearly identified and distinguished in global publishing and library systems.

History

• 1971: The system was drafted by the International Organization for Standardization to address library cataloguing problems caused by identical or changing journal titles.
• 1975: The ISSN International Centre officially opened in Paris following an agreement between UNESCO and the French government.
• 1990s–2000s: Expansion from print-only publications to digital media led to the introduction of the e-ISSN for online journals.
• Today: A global network of nearly 90 countries now manages more than 2.5 million ISSN identifiers for serial publications worldwide.

Relevance

The ISSN is operationally important across publishing, library science, and academic research.

• It distinguishes serial publications with identical or very similar names, even across countries or languages.
• It’s used by libraries and retailers for ordering, cataloguing, distribution, and inventory management.
• It enables researchers and citation systems to reference the correct serial title, reducing ambiguity.

Structure

An ISSN follows a fixed numerical format designed for consistency and machine readability. It always contains eight characters, divided into two blocks.

• Two groups of four digits separated by a hyphen
• The eighth digit is a check digit

The check digit is the eighth character of an ISSN and functions as a mathematical control mechanism. It’s  designed to detect errors that occur when an ISSN is manually typed or stored in a database. In practical terms, it acts like a verification key that confirms whether the preceding seven digits form a valid identifier.

Rather than being random, this digit is calculated using a defined formula. If the number entered does not produce the correct result, systems can immediately recognize the ISSN as invalid.

The ISSN check digit is calculated using a Modulus 11 system. This mathematical method ensures that the number sequence is internally consistent and can be verified automatically.

Formula overview

1. Each of the first seven digits is multiplied by a weight from 8 down to 2
2. All resulting values are added together
3. The total is divided by 11 to determine the remainder
4. The remainder is subtracted from 11 to produce the check digit

If the result equals 10, the check digit becomes X. If the result equals 11, the check digit becomes 0.

ISSN vs. ISBN vs. DOI

These identification systems are often confused because they appear in similar publishing and academic contexts. However, each one operates at a different level of identification and serves a distinct purpose:

• ISSN (= International Standard Serial Number) is for journals and other serial publications.
• ISBN (= International Standard Book Number) is for books.
• DOI (= Digital Object Identifier) is for digital scientific articles and online publications.

How to get

An ISSN is assigned through the national center responsible for the country of publication. The process is standardized internationally but handled locally, meaning applicants work with the authority that covers their publisher’s location.

Each country operates its own registration body within the global ISSN network:

• United States: ISSN Uplink portal at the Library of Congress
• United Kingdom: ISSN UK Centre at the British Library
• Canada: ISSN Canada at Library and Archives Canada
• Other Countries: Use the ISSN International Centre’s search tool to find your national center.

If no national center exists for your country, the application is submitted directly to the ISSN International Centre in Paris.

Authorities require proof that the serial publication exists and meets formal publishing standards. Typical documentation includes:

• Title (clearly displayed and used consistently)
• Publisher details (official name and contact address)
• Editorial information (editorial responsibility or board)
• Publication frequency (how often the serial appears or is updated)
• URL (for online publications, the website must be live and accessible)

While portals differ slightly by country, the workflow usually follows this structure:

1. Register on the relevant portal
2. Provide bibliographic details about the title, format, and launch date
3. Pay fees if applicable (registration is free in the US, UK, Canada, and Australia)
4. Wait for the reviews (from 10 working days to 6 weeks)

Not every publication qualifies. Key restrictions include:

• Only serials are eligible (books and one-time publications require an ISBN instead)
• Each format needs its own ISSN (print and online versions are registered separately)

How to find

Locating an ISSN is usually straightforward, whether you are working with a print issue or an online journal.