Why do authors post preprints?

In some disciplines, like physics and mathematics, preprints have been a well-established part of the research process. However, preprints are becoming increasingly popular across academia and there has been a recent proliferation of preprint services in a number of disciplines from biomedicine to law. The benefit of preprints is primarily speed. Because preprints are not peer reviewed, they can be made available online very rapidly. This helps authors establish primacy with their research and also makes their research available to the community quickly. Furthermore, authors can sometimes receive feedback on their preprints prior to submitting to a journal, which allows them to improve their papers before submission.