In academic world, a preprint is a draft of a research paper that has not yet been published in a peer-reviewed journal or conference proceeding. It is a way for researchers to quickly distribute new research results and receive early feedback from their peers.
Developed by the Pennsylvania State University, CiteSeerX is a public search engine and digital library and repository for scientific and academic papers primarily with a focus on computer and information science. It features autonomous citation indexing, citation statistics, and reference linking.
Maintained and operated by the Cornell University, arXiv provides access to about 880,000 electronic preprints. Covered areas include physics, mathematics, computer science, nonlinear sciences, quantitative biology and statistics.