What are preprints and how do they work

Preprints have become a standard part of how scientists circulate results. They are effective at doing one thing that traditional publishing does slowly: putting a complete manuscript in front of the whole world, free, in a matter of days. Many researchers still have practical questions about what preprints are, how repositories work, and when to post one.

What is a preprint?

A preprint is a version of a scholarly manuscript made publicly available before formal journal publication. It has not been certified through a journal’s peer review. Often it is the same paper that will later appear in a journal. Not always, though: some authors revise the text several times, and even add new results, all inside the repository where they first posted it.

Before it goes live, the manuscript passes a screening. Many repositories check submissions for scope, article type, plagiarism, and potentially harmful or inappropriate material. Those checks are not peer review, and they do not evaluate whether the results hold up. Once a submission clears them, it is posted, often within a few days, and anyone in the world can read it at no cost. Some repositories also report view and download metrics, which gives the author a direct sense of reach.

Because repositories preserve version histories, a revised version can usually be posted quickly under the repository’s policies, and the earlier versions remain part of the record. That avoids the errata and the awkward corrections that follow a paper once it is fixed in a journal issue. Revisions can also come out of the open discussion itself, through comments and new data contributed by the people who read it.

Preprints became far more visible to the general public during the COVID-19 pandemic, when the speed of the format mattered to an audience well beyond the fields that had been using it for decades.¹

Why post a preprint?

Journal publication can be slow, and peer review returns unpredictable answers on an unpredictable timeline. Preprints move faster, which makes them a strong option for research that is urgent to disseminate, such as work on epidemics or on pressing social questions. The case for that speed has been made from inside science itself: in 2016, a group of prominent life scientists argued in Science for preprints as a legitimate part of how the field communicates.²

Visibility

Speed is not the only reason preprints keep growing. The ease of dissemination, and the visibility the work earns as a result, matter to the author. Work that becomes known builds a reputation, and journals notice work that is already being read and discussed.

Evidence of productivity

A preprint often becomes public evidence of the productivity and progress of a research program. Other scientists can see it, comment on it, and in some cases propose new collaborations. It is easy to follow how results advanced and to understand the research process that unfolded after the first posting.

Accessibility

Preprints make the work readable anywhere in the world, free. That reaches many more readers, which means more chances to be followed and cited.

Speed

Some research needs results out quickly because the content itself is urgent. This is most common in health and the biological sciences, where the subject may be a pathology that needs treatment now. Preprints fit that need, because the manuscript can be public in a fraction of the time a journal requires.

What you give up

A preprint has not been through peer review, the assessment carried out by other specialists in the field before a journal publishes the work.

That absence is the whole cost of the format, and it cuts both ways. Reading a preprint means reading results that no reviewer has yet checked, so treat it accordingly when you cite one as a reference for your own research. Posting one means putting your name on results before anyone has stress-tested them, and errors that go public under your name are hard to walk back.

What is a repository?

Preprints are stored on platforms built for the purpose, usually called repositories or preprint servers. These platforms preserve manuscripts, manage versions and withdrawal policies, and support discovery by subject. Capabilities such as commenting, metrics, or direct transfer to journals vary from one repository to another.

There are many repositories, and they are generally organized by field. arXiv is the oldest and best known, covering physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics. bioRxiv is dedicated to the biological sciences. Others include medRxiv for health sciences, ChemRxiv for chemistry, SSRN for the social sciences, and Research Square across disciplines.

A brief history of the preprint

The urgency to publish is not new. Dissemination is an essential part of scientific research, arguably the most important part. And if publication is slow today, consider what it was before the internet made access easy.

In 1961, the National Institutes of Health (NIH) began circulating biological research memoranda by mail through the Information Exchange Groups (IEGs). By the time the program was shut down in 1967, under hard pushback from traditional publishers, it had circulated more than 2,500 documents among thousands of participants: a remarkable volume for scientific dissemination by post.³

After the IEGs ended, the argument about scientific communication continued and intensified. In January 1969, Preprints in Particles and Fields began operating from the SLAC library, building on preprint services at SLAC and the Lawrence Radiation Laboratory in Berkeley: a weekly list announcing new preprints, with about 1,600 subscribers within a year.

In 1991, Paul Ginsparg created an automated email server for distributing preprints at Los Alamos National Laboratory. That service became arXiv.⁴ In the years that followed, it grew alongside scientific output, expanded into more fields, and is now one of the world’s largest and best-known preprint repositories.

Today there are many repositories, separated by field, and many publishers no longer see preprints as a threat. They understand the preprint as a publication distinct from the finished work.

How to publish a preprint

Posting a preprint is straightforward, though not quite as simple as it looks. Repositories maintain quality control and screen what comes in, so submitted material goes through an analysis before it appears.

Repositories require the author to be registered. That keeps track of who is publishing and lends credibility to what is posted. Each repository sets its own rules, but in general the paper has to be scholarly in character and original, and the author has to agree to the repository’s terms for publishing the information.

So the first step is to find the repository that matches your field. Then make sure the manuscript is in good shape and can clear the screening, the same standard you would hold it to if you were submitting to a journal. Finally, read up on how your chosen repository actually works: scope, versioning, withdrawal policy, and what happens when the journal version comes out. Checking the target journal’s stance belongs in this step too: a study of major journals found preprint policies are often not even clearly stated, so do not assume.⁵

How preprints and peer review work together

The two formats are not in competition, and the workflow many fields are converging on uses both. The preprint carries the work while it is current: it goes public in days, it reaches readers and potential collaborators everywhere, and it starts collecting feedback. The journal version arrives later and records the outcome of editorial assessment and peer review. Peer review subjects the manuscript to scrutiny by specialists in the field; it does not guarantee the findings are correct, but it is the quality control the scholarly record is built on.

Scientific conferences occupy a useful middle ground between the two. Work published in conference proceedings has been through the scientific committee’s peer review, and it reaches the community at a speed much closer to a preprint’s than to a journal’s.

One piece of infrastructure connects the two versions. Crossref registers preprints as posted content, which gives the manuscript a persistent, citable DOI from the day it is posted. When the peer-reviewed version is published, the preprint’s publisher updates the metadata so each record points to the other. Galoa handles that deposit on behalf of repositories, so the work is properly identified and attributed at both stages.