The five major U.S. networks are NBC, CBS, ABC, Fox, and The CW. The first three began as radio networks: NBC and CBS in the 1920’s, and ABC was spun off from NBC in 1943. Fox is a relative newcomer which began in 1986. The CW was created in 2006 when UPN merged with The WB.
The American Broadcasting Company (ABC) is an American commercial broadcast television network that is owned by the Disney–ABC Television Group
CBS is an American commercial broadcast television and radio network that is the flagship property of CBS Corporation.
The National Broadcasting Company (NBC) is an American commercial broadcast television and radio network that is the flagship property of NBCUniversal, a subsidiary of Comcast.