A key aspect of open science is ensuring that research results are accessible, which includes removing financial barriers. Equally important is enabling others to find the research. This becomes an issue as the volume of scientific output grows, and as webpages and even entire databases are lost. Digital object identifiers (DOIs) are designed to remain identifiable through change and over time.

DOIs are widespread in scientific research, government records, and professional environments. Their immense popularity directly correlates with their utility, with an average of 1184 DOIs being used per second, as of January 2026.

In this article, we outline what DOIs are, their benefits, and how they contribute to open science.

What are digital object identifiers?

The DOI Foundation is a non-profit organization and defines digital object identifiers as:

A DOI name is a digital identifier of an object, any object — physical, digital, or abstract. DOIs solve a common problem: keeping track of things. Things can be matter, material, content, or activities.

Designed to be used by humans as well as machines, DOIs identify objects persistently. They allow things to be uniquely identified and accessed reliably. You know what you have, where it is, and others can track it too.

They look like a series of numbers with specific syntax: 10.3390/biom15121673. The slash separates the two main elements, the prefix and suffix:

• Prefix: Identifies the provider of the object.
• Suffix: This is the code that is unique to the object.

For MDPI journals, the prefix “10.3390” is used, followed by the journal’s name (or abbreviation), and a unique set of numbers.

If you have a DOI, you can add ‘https://doi.org/’ before it to create a link to the object. So, for example, the above DOI links to an MDPI paper: https://doi.org/10.3390/biom15121673.

The code is connected to metadata, which refers to data about data, such as the publication date, journal name, authors, etc. This means the object, like a research article, has a unique code, which provides direct access to the object.

Why use DOIs?

Digital object identifiers help keep track of physical, digital, and abstract objects over time. Unlike a URL, the DOI remains associated with the object regardless of any changes in the object’s web address or other metadata, as long as it is properly maintained.

DOIs are ‘actionable’, which means that if you use it, something useful will happen. In most cases, this refers to putting the DOI into a web browser to arrive at the object, whether that is a website or a data record. This is known as ‘resolving the DOI’, which is completely free to do.

Resolving the DOI via a URL is a rapid way to find source material, which in the past would have involved referring to metadata such as the author name, journal, volume, issue, and page number. Removing the requirement to manually search for material from a citation increases efficiency during the research process.

They are also clear to understand for both humans and machines, as the simple numbering system can be cross-referenced by indexers, repositories, publishers, researchers, journalists, and more.

Finally, DOIs can help increase the reach of research, as the work will remain findable and more likely to be featured in indexing services and be cited by others.

Open science: identification and access

A good way to understand the importance of digital object identifiers for open science is to look at the FAIR Data principles.

The FAIR Guiding Principles for Data Management and Stewardship emphasize standardization and machine-readability to cope with the increase in volume, complexity, and creation speed of data. FAIR stands for:

• Findability: Metadata and data should be easy to find by humans and computers.
• Accessible: The user needs to know how the data can be accessed.
• Interoperable: Data must be integrated with other data and applications for analysis, storage, and processing.
• Reusable: Data must be clearly described so they can be replicated or combined in different settings.

The goal of the FAIR Principles is to optimise the reuse of data.

DOIs contribute to or directly enable the achievement of these principles:

• The unique code is used and recognised globally, establishing an identifier that can be used by both humans and machines.
• The DOI directs the user to the object in its proper context by simply using it like a URL. This enables easy access to the object even if the metadata or host changes.
• The DOI is linked to the metadata so it can be integrated into indexing databases.
• By including DOIs in references, researchers have direct access to the object, which preserves findability even if the metadata around it change.

In short, DOIs are an effective way to ensure that objects like research articles remain findable and accessible online.

MDPI and digital object identifiers

Since 2008, all MDPI articles obtain a digital object identifier to ensure permanent retrievability and the ability to cross-reference citations. They are also applied to all MDPI Books and entries on Preprints.org.

For MDPI academic journals, the prefix “10.3390” is used, followed by the journal’s name (or abbreviation), and a unique set of numbers. These numbers correspond to the journal’s Volume, the Issue, and the article number of each specific publication.

Ensuring all articles have DOIs furthers MDPI’s overall mission to advance scientific communication. Assigning DOIs to all output in MDPI journals, books, and preprints focuses on the long-term preservation of research, ensuring they appear in leading scholarly indexes and can achieve the biggest impact possible.

Ensuring research is accessible and impactful

Digital object identifiers help keep track of physical, digital, and abstract objects over time. They ensure that the object remains findable and accessible even if the context of it changes.

MDPI ensures that all papers receive a DOI because it is dedicated to advancing scientific communication, of which permanent records and findable research are highly important aspects.

Click here for our article, All You Need to Know About Open Access, which covers a range of topics that can help boost your understanding and also keep you up to date.