Preprints are early versions of full research articles that have not been peer reviewed. You should not upload as a preprint the version of a paper that has already been published or was accepted to be published in a peer reviewed journal, unless your journal specifically allows for this. Preprints are assigned a Digital Object Identifier (DOI) upon posting. Posting published and accepted to be published work creates an additional DOI running the risk of confusing readers and splitting potential citations. For more information on what a preprint is see the FAQs.