Preprint
Appearance
A preprint is a draft of a scientific paper that has not yet been published in a peer-reviewed scientific journal.
Some preprints are great science -- some are mediocre -- some are nonsense. There is no external quality control.
However, scientists read one another's pre-prints avidly, in an attempt to keep current in their fields. Pre-prints by highly respected authors are often regarded as more legitimate than others, pending confirmation of this by the peer review process.
In recent years, preprints have started to be avalable online.
Online sources of preprints: