Digital Object Identifiers

20 Years of DOIs

Citavi and other reference management programs let you easily add the citation information for scholarly journal articles when you import PDF files, search in your browser, or enter a DOI name directly.  Seeing the fields automatically fill up with information is almost like magic and can save you a lot of time that you’d otherwise need to type everything in by hand. You just need to give the information a quick check and then you have everything you need to automatically generate a bibliography.

There’s no question that DOIs are incredibly useful, but have you ever stopped to wonder what they are exactly? What does the abbreviation “DOI” stand for and how exactly do DOIs make it possible to auto-populate source information? And where does all the bibliographic information come from that Citavi imports? Read on below to learn more.

What is a DOI?

DOIs are just one example of what’s known in the library world as a “unique identifier”. With the help of unique IDs, objects, such as books, articles, and journals, can be precisely identified. You’re likely familiar with the ISBN number found on the back of the book, but there are also ISSNs (International Standard Serial Number) for journals. DOIs are the unique identifiers for individual journal articles. You’ll usually find the DOI name on articles either at the beginning or end of the article, but they can sometimes be found in the footer as well:

DOIs aren’t the only unique identifiers used by academic journal articles. In the Life Sciences articles indexed by the database PubMed are assigned a PMID. In arXiv, a pre-print and open access database primarily for Physics, an arXiv ID is used. However, DOIs are different because they’re used across all subject disciplines.

The abbreviation DOI stands for “Digital Object Identifier” and is a registered trademark. The purpose of the DOI is to provide a permanent link to a digital object, such as an academic journal article. The standard ISO 26324 sets forth the format and structure of a DOI. A DOI is assembled from a combination of numbers and letters, for example:


DOIs always begin with “10”. After that the number for the publisher or other organization is given. A backslash follows along with a unique “DOI suffix”:


The DOI suffix can vary and can even be based on another system, such as the ISBN. For example, an ebook might have the ISBN “978-3-030-04943-0”. A chapter from the ebook could then have the DOI “10.1007/978-3-030-04943-0_5”. The number “1007” stands for the publisher Springer, while the five at the end stands for the fifth chapter in the book.

It’s also possible to use letters for a descriptive DOI suffix. For example, this article from the journal PLOS ONE has the following DOI: 10.1371/journal.pone.0229432

If you place in front of the DOI, you’ll get a clickable URL:

The standardization of these links were one of the last big changes that Crossref made to its display guidelines for DOIs. Who or what is Crossref? We’ll take a look at that question below.

Who is responsible for the DOI system?

The Digital Object Identifier was developed by the publishing industry. The introduction of the DOI system was announced in 1997 at the Frankfurt Book Fair. At this time the International DOI Foundation was also founded to manage the assigning of DOIs and the maintenance of DOIs in a central database.

However, it wasn’t until 2000 that the DOI registration agency Crossref began assigning the very first DOIs to academic journal articles. Crossref is a service provider that carries out all of the work involving DOIs on behalf of the academic publishing world. Since the assigning of DOIs didn’t start until 20 years ago, articles published before 2000 often don’t have a DOI unless they were assigned one retroactively. Ten years after it started, the DOI system finally became an ISO standard in 2010.

In addition to Crossref there are additional registration agencies for other types of items, such as  DataCite for research data sets or the Entertainment ID Registry (EIDR) for the entertainment industry. The International DOI Foundation coordinates the work of the registration agencies, checks that DOIs are used correctly, and determines the rules for assigning DOIs.

If you want to find out which registration agency registered a particular DOI, you can paste the following prefix in front of it and search for it in your browser:

For example, this DOI is registered with Crossref:

If your institution wants to index its academic articles in Crossref, it needs to be a Crossref member, which requires a yearly membership fee and additional costs for each DOI registration. That’s also the case for other registration agencies, such as mEDRA.

How do DOIs work?

Strictly speaking, a DOI such as “10.1str080/10841806.2020.1750212” is known as a “DOI name”. This DOI name permanently links to the actual content of the digital object. But why can’t the content be linked directly?

Before the DOI system was introduced, dead links were a big problem. As more and more journal publishers switched from offering only print publications to offering both print and online or even online only articles, their online presence changed rapidly. It could easily happen that a website was updated and then the link to a published journal article would no longer work. If this link had previously been added to a bibliography, readers would then no longer be able to locate the source.

The DOI system was introduced to solve this problem by establishing unique permanent links for each article.  Even if the link to the article itself was later changed, the DOI for the article was not affected and remained the same.

In addition to the link, other useful metadata is also associated with the DOI. In other words, the DOI is more than just a typical redirect. The DOI lets you do the following:

  • The document’s full text can be downloaded from different providers.
  • The metadata for the object can be downloaded.
  • The document can be forwarded.
  • The author can be contacted

Because the metadata is saved under the DOI name, the reference management program Citavi can add the citation information via a DOI search in the registration agencies Crossref and DataCite. The downloading of full-text also happens via these registration agencies.  And if you use the Citavi Picker to import the references cited by an article, this information also comes from Crossref.

As you can see, the DOI system truly makes life easier for academics. So, the next time you import journal articles into your reference management software, we hope that you’ll take a moment to celebrate 20 years of DOIs.

Are you also a fan of DOIs? Did we leave out any important details in our blog post? We’d love to hear from you on the Facebook post for this blog article or by email at


For Further Reading:

Digital Object Identifier System Handbook (2020). Available online at, updated February 17, 2020, accessed on October 8, 2020.

Created by: Jana Behrendt – Published on: 10/20/2020
Tags: Good to know

About Jana Behrendt

Jana Behrendt, a librarian by training, is deeply interested in everything related to personal information management. However, she does not read as much as you would expect from a librarian. She loves hiking in the Swiss Alps – as long as she doesn’t have to look down.

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