What is a Digital Object Identifier (DOI)?

June 29, 2017reference

If you’ve ever looked through scientific papers, trade journals, or data sets you’ve likely encountered a Digital Object Identifier. This post aims to demystify them, at least in terms of what they represent.

A diagram of the sections of a DOI

The Digital Object Identifier (DOI) system is a standard of assigning identification numbers to publications of data. Within the DOI system, objects are assigned DOI names. A single DOI name is commonly and simply referred to as a DOI®.

DOIs are:

  • Unique: No two DOIs will ever be the same
  • Permanent: Once a DOI is assigned it can never be deleted or revoked
  • Designed to work within browser URLs, among other places

It’s also important to note that the “digital” in DOI refers to the identifier itself, and not the object. DOIs are designed to share identifiers over digital networks, not to describe digital-only objects.

How are DOIs Constructed?

DOIs follow a specific format and syntax. On a high level it is a prefix, a separator in the form of a forward slash “/”, and then a suffix.


The prefix of a DOI is how the regulatory and public is identified. In an example of 10.4211, there are two main elements separated by the full stop period “.”:

  • Directory Indicatior: 10
    This number will always be 10. This means that it is a DOI. Whenever you see 10.__/___, you know you’re dealing with a DOI.
  • A Registrant Code: 4211
    This signifies the organization that is publishing the data. Each data publication from a registrant will always have the same 4211.

Note that a registrant code can also have a subdivision separated by a full stop period “.”, something like 10.1000.10. These may or may not have relevance in an actual taxonomy, though they do have implications when it comes to resolution, or retrieving the document.


The format of the suffix, on the other hand is fairly flexible, so long as it is unique. It can be any ISO standard identifier, such as ISBN, ISSN, or numerous others. Alternatively, it can be a custom identifier.

Here are some examples of suffixes:

  • An ISSN Number
  • A HydroShare Resource
  • Completely Custom

Conclusion and References

There you are! I hope this guide was helpful and that my own work trying to demystify these.

  • For more information about HydroShare, visit
  • For more information about DOIs, visit the DOI Handbook

Mark Robert Henderson

Mark Robert Henderson lives in coastal Massachusetts and works for the creators of OrbitDB.  The best way to reach him is via e-mail.

This website does not track you.