If you run a journal, two identifiers come up constantly: the ISSN and the DOI. They are easy to confuse, but they solve different problems.

What an ISSN does

An ISSN (International Standard Serial Number) identifies your journal as a whole — the serial publication. Print and online editions each get their own ISSN.

What a DOI does

A DOI (Digital Object Identifier) identifies a single article and gives it a permanent link, even if your website structure changes later.

Why you need both

The ISSN registers the journal; the DOI makes each article permanently citable and discoverable. Professional journals use both together.