Digital Object Identifier System
DOI: Persistent Identifiers for Scholarly Research Objects · Also known as: DOI, Digital Object Identifier, persistent identifier
A Digital Object Identifier (DOI) is a unique, persistent alphanumeric code that identifies a scholarly work (journal article, book chapter, dataset, preprint) and persists even if the URL changes. Introduced in 1998 by Norman Paskin and the International DOI Foundation, DOIs are now standard in academic publishing. They consist of a prefix (assigned to a publisher or organization) and a suffix (assigned to an individual work), formatted as 10.XXXX/XXXXX (e.g., 10.1371/journal.pmed.1000097). DOIs are registered with international agencies (CrossRef, DataCite, mEDRA) and resolve through the centralized resolver https://doi.org/, ensuring that a DOI will direct users to the correct article regardless of whether the publisher's website changes location.
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When to use it
Include DOIs in citations whenever available. DOIs are standard for journal articles, book chapters, and datasets. If a DOI is not present (e.g., for older articles published before DOI adoption, or some grey literature), cite the URL or other identifier instead. When writing systematic reviews, evidence syntheses, or any research that must be reproducible and verifiable, DOIs are essential. Funding agencies (NIH, NSF, EC) now require DOIs for reporting research outcomes. If you are publishing a preprint, dataset, or research software, obtain a DOI to ensure long-term preservation and citability.
Strengths & limitations
- Persistence: DOIs are designed to persist indefinitely, unlike URLs which can break. A DOI registered today will resolve in 50 years.
- Standardization: DOIs follow an international standard (ISO 26324) and are recognized across all academic databases and publishing platforms.
- Discoverability: DOIs enable tracking of citations and impact. CrossRef and other DOI agencies maintain metadata that feeds into citation databases (Scopus, Web of Science).
- Interoperability: DOIs link articles to funding information, author identifiers (ORCID), and datasets, creating a connected scholarly ecosystem.
- Machine-readability: DOI metadata is structured and queryable, enabling automated citation extraction, reference matching, and research assessment.
- DOIs are not universal: older articles (pre-2000), some grey literature, and non-English publications often lack DOIs.
- DOI registration requires publisher or repository infrastructure; self-published or highly dispersed works may not have DOIs.
- DOI resolution depends on the centralized resolver (https://doi.org/); if the resolver is unavailable, DOIs cannot be resolved (rare, but theoretically possible).
- Incorrect DOI metadata: if a publisher registers incorrect metadata (wrong author names, wrong article title), the metadata in DOI registries will be wrong, potentially causing citation errors.
- Limitations of free DOI services: Zenodo and figshare provide DOIs for preprints and datasets, but these are less established than publisher-assigned DOIs and some funders may not recognize them equally.
Frequently asked
Do I need to include both the DOI and the URL in my reference list?
No. Include the DOI preferentially; it is more persistent than a URL. In APA 7th edition, list the DOI as a URL (https://doi.org/10.XXXX/XXXXX) and omit the journal's website URL. If a DOI is not available, include the URL instead. You should not list both in the same reference.
What if an article has both a print DOI and an online DOI?
Some hybrid journals issue separate DOIs for print and online versions. Cite the version you accessed. If you accessed the online version, use the online DOI. If the article appears in both print and online and they are assigned the same DOI, this is preferable and avoids confusion. Consult your publisher or the journal's citation guidelines for clarity.
Can I register a DOI for my preprint, or do I need to wait for journal acceptance?
Yes, you can register a DOI for a preprint immediately. Services like Zenodo, figshare, and arXiv assign identifiers; Zenodo issues DOIs. This ensures your preprint is discoverable and citable. If your preprint is later published in a journal, the journal will assign a separate DOI to the published version. You should cite the published version (which has its own DOI) in your own later work, but citing the preprint is acceptable if the published version is not yet available.
What happens if a DOI resolver is temporarily unavailable?
The https://doi.org/ resolver is maintained by the International DOI Foundation and major publishers, with high redundancy and uptime. Outages are extremely rare. If you cannot resolve a DOI temporarily, try again later, or use an alternative resolver (e.g., https://dx.doi.org/). In your citation, cite the DOI itself (not the resolver URL), so your reference is robust to resolver changes.
Sources
- Paskin, N. (2010). Digital Object Identifier (DOI) system. Encyclopedia of Library and Information Sciences, 3rd ed., 1586–1592. ISBN: 978-0-8493-9712-7
- Crossref: The scholarly link network. https://www.crossref.org link ↗
- International Organization for Standardization (ISO). (2012). ISO 26324:2012 Information and documentation - Digital object identifier (DOI). ISO. link ↗
How to cite this page
ScholarGate. (2026, June 3). DOI: Persistent Identifiers for Scholarly Research Objects. ScholarGate. https://scholargate.app/en/research-skills/doi-system
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
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