BITNET was a co-operative U.S. university computer network founded in 1981 by Ira Fuchs at the City University of New York (CUNY) and Greydon Freeman, Inc. at Yale University. The first network link was between CUNY and Yale.

.bitnet was a pseudo-domain-style suffix used in the late 1980s when identifying a hostname not connected directly to the Internet but possibly reachable through inter-network gateways. In this case, it indicated that the hostname preceding it was reachable via the BITNET network. This was one of several apparent "top-level domains" that were not actually in the Internet Domain Name System (DNS) root, but were sometimes used in addresses during the time when non-Internet networks remained in wide use.