Definitions for "On-line service"
usually means a pay service such as Compuserve or GEnie.
A company that provides customer only content to subscribers of their service. Most On-line services now offer Internet access, but their main feature is the privately maintained network that is only accessible to their customers. This network is not part of the Internet, although some On-line services are currently making some content available on the Web. Examples: AOL, MSN, Compuserve, Prodigy
A service, such as CompuServe or America Online, that provides access to a network of information, services and a community of other subscribers as well as to the Internet.