What is a DOI: How to Find and Use It in Academic Writing

Many students ask, “What is a DOI?” as they often encounter this element when researching. DOIs have become increasingly important in academic writing as they help ensure accurate and consistent citation practices. In this article, we’ll shed light on the definition of this term and its use in various formatting styles.

What is a DOI

DOI meaning and role in academic writing 

Digital Object Identifier (DOI) is a unique alphanumeric code assigned to a digital object, such as a book, journal article, or report, proceeding it provides a persistent and reliable way to locate and access the source online. Additionally, it is referred to as a permalink. These elements are utilized for various academic and non-academic sources found online. That’s why MLA, APA, and other academic formatting styles recommend including DOIs in references.

How to find a DOI?

In journal articles, this element is usually located in the upper part of the page, nearby the title, writer's name, and other publication details. When downloading PDFs of journal articles from academic databases, the DOI number is commonly included at the bottom of every page or cover page.

When finding the DOI number is difficult, an alternative method is to apply Crossref. By copying and pasting the pertinent information into the ‘Search Metadata’ box, you can search for the DOI. If it’s not found, likely, the article does not possess one. In such instances, including a URL as an alternative reference is appropriate.

Using DOIs in APA style

According to APA guidelines, including a DOI whenever available is recommended. The majority of academic books and journal articles are typically assigned DOIs. To detect this element, refer to the book’s copyright page or the article’s first page. If the identifier cannot be found, it can be omitted from the APA citation. In the 7th edition of APA guidelines, DOIs should be formatted as URLs, starting with “https://doi.org/” followed by the identifier itself.


Smith, J. D., & Johnson, A. B. (2022). The impact of climate change on biodiversity. Environmental Science Journal, 15(3), 234-248. https://doi.org/10.1080/1234567890

Using DOIs in MLA style

In this format, if a DOI is accessible for a source, including it in the citation is advisable. To understand how to cite DOI in MLA, see an example of the same article with this element.


Smith, John. “The Impact of Climate Change on Biodiversity.” Environmental Science Journal, vol. 15, no. 3, 2022, pp. 234-248. doi:10.1080/1234567890.

Using DOIs in Chicago style

DOIs are commonly used in Chicago style when available. You should put the identifier at the end of your reference to incorporate the identifier into a citation, the preferable style of formatting is https://doi.org/10.1080/1234567890.


Smith, John. “The Impact of Climate Change on Biodiversity.” Environmental Science Journal 15, no. 3 (2022): 234-248. https://doi.org/10.1080/1234567890.


Are DOIs and URLs the same? 

No, they are different. While both are used to locate digital resources, they serve different purposes. DOIs are unique alphanumeric strings assigned to digital objects, providing a persistent identifier that remains unchanged even if the location changes. URLs, on the other hand, are dynamic web addresses that can change over time. DOIs provide a higher level of persistence and stability compared to URLs.

Why are DOIs important? 

DOIs serve as distinctive identifiers for digital papers. They play a crucial role in academic citations due to their long-term stability, surpassing URLs and ensuring readers can access the cited source consistently. Online books and journal articles are commonly hosted on various websites and databases. While the URL of a specific page hosting an article can undergo modifications or become outdated, a DOI remains linked to the particular document, providing a constant and unchanging reference point.

How can I find DOIs for articles? 

These elements are commonly located next to the author and publication details in the upper part of an article page. Alternatively, you can find them on PDFs of virtual journal articles, a dedicated cover page, or at the bottom of every page.

When is it appropriate to use a DOI instead of a URL?

Always prioritize using a DOI when it’s available for the source. Avoid relying on the URL if a DOI is provided. However, in cases where the material lacks a DOI, include the URL in your citation instead.

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