What is a Preprint? A Complete Guide
Research
Research
Research
Research
Preprints are reshaping how scientific knowledge moves through the world. This page explains what preprints are, why they exist, how to read them critically, and how the preprint ecosystem compares to traditional journal publishing.
A preprint is a research paper that has been made publicly available before — or sometimes instead of — formal peer review by a journal. The author uploads the paper to a preprint server (like arXiv, bioRxiv, SSRN, or Expertini Research), where it immediately becomes accessible to anyone in the world.
The key distinction from a published journal article is that a preprint has not been evaluated by independent expert reviewers as part of a formal journal process. It represents the author's own account of their research, in the form they have chosen to share it.
Preprints are not a new concept. Physicists have been sharing preprints via arXiv since 1991. The COVID-19 pandemic accelerated preprint adoption dramatically across medicine, biology, and public health, as researchers shared findings months before journals could publish them.
Several reasons, all legitimate:
This is the right question to ask — and the honest answer is: it depends on the paper, and you cannot know without reading it critically.
Preprints have not been through formal peer review, which means the methodology, data analysis, and conclusions have not been independently evaluated by experts in the field. Some preprints contain significant errors that peer review would catch. Others are high-quality work that would pass peer review with minor revisions.
The track record during COVID-19 is instructive: some preprints turned out to be highly influential and held up well under scrutiny; others made claims that did not survive independent replication.
Reading a preprint requires the same critical evaluation skills as reading any scientific paper — plus an extra degree of scepticism about unreviewed claims. This is not unique to preprints: peer review does not guarantee correctness either, as retractions of peer-reviewed papers demonstrate.
The main differences:
Yes — preprints can be cited, and increasingly are. The key is to be transparent about what you are citing.
When citing a preprint, your citation should clearly indicate that it is a preprint and name the server it is hosted on. A typical APA citation would look like:
Author, A. (Year). Title of paper. Expertini Research [Preprint]. https://doi.org/10.XXXXX/...
Before citing, always check whether a peer-reviewed version has since been published. If it has, cite the published version instead — it may differ substantially from the preprint.
Some journals and funding bodies have policies about citing preprints in grant applications and manuscripts. Check the specific requirements of your target venue.
Always prefer the published (peer-reviewed) version if it exists. The published version has been through external evaluation, may contain corrections based on reviewer feedback, and has a stable, permanent citation record via the journal DOI.
Cite the preprint when:
The main general and discipline-specific preprint servers:
In most cases, no. The majority of major researchers — including Springer Nature, Elsevier, Wiley, IEEE, and the American Chemical Society — explicitly permit preprint posting before or during journal submission. This is sometimes called a "Sherpa/RoMEO green" policy.
However, a minority of journals have stricter policies. Always check the specific journal's preprint policy before posting. The Sherpa/RoMEO database (sherpa.ac.uk/romeo) lists policies by journal and researcher.
When you submit to a journal, always disclose that a preprint exists. This is good practice and is required by many journals.
Free, immediate, Google Scholar indexed. No APCs.