An online information service that provides access to the Internet, e-mail, instant messaging and an integrated contact list. Founded in 1969 as a timesharing service, CompuServe is one of the oldest online services, being the first to offer e-mail in 1979 and online chat a year later. The GIF graphics format was developed by CompuServe in 1987 to transfer compressed images over the very low-speed, dial-up lines in common use at that time. GIF images are widely used on Web sites; however, the compression method in GIF is owned by Unisys.

In 1998, CompuServe was acquired by America Online (AOL), and whereas AOL is geared more to the consumer, CompuServe's offerings have been aimed at the professional business user. Specialized versions of CompuServe are also available for the legal, insurance and airline industries. See online service.