CompuServe (CompuServe Information Service, also known by its acronym CIS) was the first major commercial online service in the United States. It dominated the field during the 1980s and remained a major player through the mid-1990s, when it was sidelined by the rise of services such as AOL with monthly subscriptions rather than hourly rates. Since the purchase of CompuServe's Information Services Division by AOL, it has operated as an online service provider and an Internet service provider. The original CompuServe Information Service, later rebranded as CompuServe Classic, was shut down July 1, 2009. The newer version of the service, CompuServe 2000, continues to operate.

CompuServe was founded in 1969 as Compu-Serv Network, Inc. (the earliest advertising shows the name with initial caps) in Columbus, Ohio, as a subsidiary of Golden United Life Insurance. While Jeffrey Wilkins, the son-in-law of Golden United founder Harry Gard, Sr., is widely credited as the first president of CompuServe, the initial president was actually Dr. John R. Goltz. Goltz and Wilkins were both graduate students in electrical engineering at the University of Arizona. Early employees also recruited from the University of Arizona included Sandy Trevor (inventor of the CompuServe CB Simulator chat system), Doug Chinnock, and Larry Shelley. Wilkins replaced Goltz as CEO within the first year of operation.