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What is a digital object identifier?

Digital object identifiers (DOIs) are permanent digital tags that can be used to uniquely identify pieces of intellectual property on digital networks. DOIs are widely used to identify academic and professional publications, such as journal articles, books and book chapters, reports, and datasets.

The DOI system was introduced in 2000. The system is governed by the International DOI Foundation (IDF). The DOI system’s purpose is to prevent information objects from becoming lost as they move and their URLs change on the internet. Registration agencies such as Crossref in academic publishing coordinate the assignment of DOIs, with 275 million DOIs assigned to date. There are over 5,000 assigner organizations, including academic publishers, that make sure that the DOI points to the current location of the published item.

For academic publishers, the ability to attach a DOI at any level of granularity, whether to a journal article, book, book chapter, or even to a citation, enables academic publishers to make content permanently accessible. Identifying objects rather than locations means that content never gets lost.

What does the DOI look like?

The DOI has two parts, a prefix and a suffix, separated by a slash, for example 10.2478/jdis-2021-0030. The prefix identifies the organisation that registered the DOI. This usually takes the form 10.NNNN where NNNN is a four digit number greater than or equal to 1000 and the „10” identifies it as part of the DOI system. In this case, the prefix is 10.2478 and identifies the article as published by De Gruyter, of which Sciendo is a part. The suffix jdis-2021-0030 identifies the specific piece of intellectual property. In this case, it identifies article 30 published in 2021 in the Journal of Data and Information Science. This suffix is decided by the publisher.

Permanent identifier

The primary benefit of a DOI is that it is permanent. The DOI is unique and remains fixed over the life of an object. The DOI can be attached to metadata about the object and won’t change, whilst the location of the objective and other metadata may change. If an object moves, the DOI infrastructure is updated by the assigner organisation to reflect the move. This means that readers are always directed to the object when they click the DOI, even if an object has moved to a new location or website.

Referring to an online document through its DOI provides a more stable and permanent link than directly using a URL.

Impact measurement

DOIs make it easier to measure impact from research, such as numbers of views and downloads, use in government documents and news sources, and mentions on social media. Many of the tools that measure impact use DOIs to capture data related to content usage across different platforms. Whereas it can take months to years for traditional citations to appear in the academic literature, mentions in social media can provide an immediate measure of impact. So by including the DOI in all references to a publication, whether a social media post or a citation, it helps to improve the visibility and usage of any research.


Research shows that journals and books with DOIs have a higher average number of citations than those without a DOI. They are more visible and more easily found. DOIs also address one of the major historic problems with research citations, which is broken links. Many web addresses disappear within a few years of being cited, an effect known as 'link rot’. The persistent nature of the DOI prevents this. By using a DOI in your referencing of your and others’ works, and having other academics reference your work with the DOI, you can be sure that citations will always be accurate and point to the published version of the article. The DOI is a guaranteed location for the item cited because it will always resolve to the current web address.

Using DOIs in reference lists and bibliographies

  1. Using the Crossref DOI URL as the permanent link. For example: Thelwall, M., & Thelwall, S. (2021). How has Covid-19 affected published academic research? A content analysis of Journal Articles Mentioning the Virus. Journal of Data and Information Science, 6(4), 1–12.
  2. Displaying the text Crossref with a permanent DOI link behind the text. For example: Thelwall, M., & Thelwall, S. (2021). How has Covid-19 affected published academic research? A content analysis of Journal Articles Mentioning the Virus. Journal of Data and Information Science, 6(4), 1–12. Crossref.