What is a preprint?

With the rise of new preprint servers, and especially multiple offerings in the same discipline, some effort should be put into thinking about what it is that makes a preprint a preprint. This post is my take on the issue.

A preprint is about three aspects: content, availability and timing.


The preprints we are concerned with are additions to the research literature. To state the obvious, any work following the scientific method should qualify. The question then is how widely should the net be thrown to include other article types? It should be uncontroversial to include research articles, reviews and essays which form the backbone of output in science and the humanities. However, the literature includes a lot more: editorials, opinions, comments and so on. In addition, the concept of micropublication has been suggested, i.e. publishing a single part of a traditional paper, such as only the methods, results or discussion. With the current publishing paradigm, one could suggest including anything that could be published in a journal could be made a preprint, but thus is unsatisfactory as the role of journals might unexpectedly change and journals have individual policies. It also excludes work at a more preliminary stage. I think it is useful to split the literature into 1) research: hypothesis driven investigation and 2) grey literature: informed conversation about research (written by researchers). Both could be considered for preprints, but highlighting the difference via an assigned article type should be done in practice.


A preprint should be available to anyone. I would qualify this by saying that open access is desirable but not necessary: A basic definition of a preprint should permit a broad range of copyright and licensing criteria. Would it be acceptable to paywall a preprint? I would argue strongly against this option and it seems quite pointless, but don’t think it should discount something as being classed as a preprint.


Preprints are about reporting work at the earliest possible stage. “pre” in the name is because they come before validation by the research community.

The primary mode of validation currently is peer review and journal publication, but the definition shouldn’t be restrictive. New processes of confirming results could emerge in the future and should be connected to preprints. Grey literature is usually not peer reviewed, so editorial review and publication is sufficient to count as validation.

Should postprints or accepted versions of papers be mixed in with preprints? The difference between what is a preprint and postprint should be about when the first version is put online. In practice, it is acceptable to update a preprint with an new version, including a peer-reviewed one. The lack of a fixed end point is, to my mind, a strength of preprints and should be permitted within a working definition. As outlined below, there are situations where it is critical to know if something has been peer reviewed, so there should be a differentiation between the two.


In summary, I would define a preprint as a piece of research made publicly available before it has been validated by the research community.

Not to be confused with the above, and a topic for a future post is the question of what is a preprint server. Not all preprints appear on a preprint server and not everything that appears on a preprint server is necessarily a preprint.

Does it matter?

A number of preprint servers don’t publish preprints strictly according to this definition, for example by allowing publication of an abstract without full text, or permitting uploads of post-prints or accepted versions. I don’t think most scholars care a great deal about this, but it is important in some circumstances. For preprint aggregators, funders, journalists, medical practitioners and in research assessments it is much more important to know what has not been peer-reviewed and whether something is simply an opinion as opposed to reporting research outcomes. For this reason, the distinction between research and grey literature, and preliminary and reviewed work should be made clear.

In the spirit of preprints, I would be interested in feedback on the definition and how it can be improved. Please comment or get in touch by some other means.

2 thoughts on “What is a preprint?

  1. Chris Winchester says:

    Thanks for this useful article. In your view, could a congress poster be considered a pre-print? In contrast to the congress abstract on which it is based, it is not itself peer-reviewed.


    1. Martyn Rittman says:

      Interesting question. I think it depends more on the content than the form. Personally, I wouldn’t consider editorial review of the abstract to confer acceptance of the whole poster content. On the other hand, I can’t imagine preprint servers starting to accept posters on their platform.


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