The Crossref Curriculum

Persistent identifiers

A persistent identifier (PID) is an ongoing, long-lasting digital reference to a resource.

An identifier is a label which gives a unique name to an entity: a person, place, or thing. Unlike URLs, which may break, a persistent identifier reliably points to a digital entity. Digital object identifiers (DOIs) are persistent identifiers for entities such as journal articles, books, and datasets. You may have heard of ORCID iDs, which are persistent identifiers for researchers, and DataCite, which assigns DOIs for datasets. Learn more about the critical role of the DOI.

Crossref, ORCID, DataCite, and many other PID organizations work together to build trusted connections between DOIs, ORCID iDs, and other identifiers.

PID map: identifying and linking research elements. We identify researchers using ORCID iDs, works using DOIs, research institutions using Organization IDs (ROR), and funders using Funder IDs. Grant IDs identify grants, and research equipment and materials. Having uniquely identified each element, we include relevant PIDs in the metadata of each element. The links show the relationships between the elements, and allow us to see how they are connected in time and space.

Learn more about the work of DataCite, ORCID, and the Research Organization Registry (ROR).

DOIs are one of the most-used persistent identifiers in scholarly communication, and are used across disciplines. Read on to learn more about DOIs, their structures, and how to register them with Crossref.

Last Updated: 2020 April 8 by Laura J. Wilkinson