A preprint server is a data repository that hosts scholarly articles before they have been formally peer-reviewed and published. Typically, the author(s) of a paper will upload a draft version to the preprint server, which generates a publicly accessible URL where the paper and any other relevant data may be viewed, downloaded, or shared. Because the peer review process can often take months or even years, preprints are a quick way to circulate research outputs and data. However, authors of preprints may seek formal publication after uploading to a preprint server. Preprint servers can be discipline-specific (e.g., bioRxiv), regional (e.g., AfricArXiv), multidisciplinary (e.g., arXiv, SocArXiv), or general purpose (e.g., Zenodo). Preprint server is a Casebook value under the "Network Terrain" variable in the code book.