BILL CLINTON and Al Gore made a campaign promise to help build a national data network, hoping it would lead to new digital information services. While waiting to see if the new Administration follows through, businesses can get a taste of the future with the rapidly growing commercial networks of computer services.

The first networks were on-line services like Prodigy, Compuserve and America Online. Although they provide useful services, these networks are based on minicomputer and mainframe technologies of the 1960's and 1970's, in which thousands of users can connect simultaneously by telephone to a central system that dispenses electronic information. And that technology has drawbacks: the systems can become congested, and for the most part customers have limited options.

In sharp contrast is the Internet, a collection of computer networks that does a little of what a national data highway would do and that already has hundreds of thousands of computer users.

The Internet is a web of networks with shared software standards, allowing users on one network to reach anywhere into a global thicket. Created by the Pentagon, the Internet was originally limited to academic and corporate researchers and government officials. It began as a simple mechanism for sharing data, using remote computers and exchanging electronic mail. Now it contains large and small, commercial and nonprofit networks that offer a remarkable array of services.