DOI for objects

DOI (Digital Object Identifier) is a digital identifier for objects in the digital environment. An object can be, for example, articles, datasets, and other types of content. DOIs make these outputs uniquely identifiable, traceable, easily citable and reusable. 

Along with each DOI assigned to a digital object, metadata describing the object and a URL where the metadata and information about where the object is available are permanently registered. Thus, even if the object is moved to a different location than the original, the DOI still refers to the current information about where the object can be found.

The DOI is an alphanumeric code that contains:

  • address –
  • prefix – always starting with “10.”, indicating the organisation or repository that assigns the DOI
  • suffix – indicates a specific digital object

The syntax and other functional components of the DOI system are specified by ISO 26324:2022

Registration agencies

The DOI system was established in 1997, the same year the International DOI® Foundation was founded to sponsor it. Under the Foundation, so-called registration agencies are created.

Registration Agencies provide services to DOI assigning institutions such as prefix assignment, DOI registration, and the provision of infrastructure to register and update metadata for digital objects.

Agencies can then provide other value-added services such as searching the metadata of objects with an assigned DOI.

Crossref is the largest registration agency for DOI allocation. It focuses on DOI assignment in the publishing process, typically for publishers. Crossref is thus used by e.g. university presses and professional journals to assign DOIs to books or journal articles.

In contrast, the DataCite registration agency focuses on assigning DOIs to objects that have not gone through the traditional publishing process, such as datasets, theses, reports, etc. DataCite thus makes it possible to assign a DOI to, for example, a dataset that serves as the basis for a published article, thus making it possible to easily link the two outputs. 

This decision tree shows which agency is more appropriate for which context. Organisations can use the services of both registration agencies at the same time.

You can search metadata of the DOIs registered with DataCite and related entities (DOIs registered via Crossref, objects’ authors, etc.) here:

Video tutorials on DataCite (metadata, citations, Fabrica, API) can be found on the DataCite Trainings YouTube channel.


For more information about DOI and how to support its use at your institution, contact the National DOI Centre at

Used sources:
DOI Foundation [online]. Wilmington (Delaware): International DOI Foundation, c2022 [cit. 2023-02-01]. Available at:
DOI Handbook [online]. Wilmington (Delaware): International DOI Foundation, 2019 [cit. 2023-02-01]. Available at:
DataCite Support [online]. Hannover: DataCite [cit. 2023-02-01]. Available at: