The first thing you have to know about Apple's fascinating new "Hypercard" for the Macintosh series of computers is that Hypercard is not a card -- at least, not in the traditional sense of that word within the personal computer universe.

That is, Hypercard is not a separate circuit board that you install inside the machine. It's a software program that is available on disks to anybody who owns a Mac already, and will be built into all new Macintosh machines (in the form of a ROM chip) starting in September.

In fact, the whole concept of a separate circuit board, or "card," is quite alien to the principle underlying Apple's Hypercard program. Lots of computer owners find the idea of opening the case of their machine and installing a circuit board to be perfectly terrifying. There's no reason for this, frankly -- installing a new board in a computer is about as complex as changing a light bulb -- but there's no question that many people think of circuit boards as complicated, technical and scary.

Apple's Hypercard, in contrast, is meant to be simple, approachable and friendly. It is a powerful data-base program implemented in such an easy, unthreatening style that anybody can use it. Computer users who wouldn't dream of tackling the anfractuosities of a programming language like DBase III on the IBM-PC can -- in theory, at least -- create data-base systems just as powerful in the cheerful environs of Hypercard on a Macintosh.

Hypercard was THE hot new item at the Macworld Expo in Boston earlier this month. The initial gush of praise for the program was so effusive that you would have thought its name was "Hypecard." This reception was, perhaps, slightly excessive -- but that should not obscure the fact that Hypercard is a fascinating new use of personal computing power.

A data-base program is basically a means for collecting and manipulating information. Let's say your store has 42 sales people, and you want to keep track of their performance on the job and their status within your company. You could try to enter all the detailed information about each employe on index cards and keep the stack of cards in a desk drawer. But the better idea is to keep all the same information in a computerized "data base" -- in essence, a collection of electronic index cards stored in a corner of your hard disk.

Then when you need a particular tidbit of information about any or all of your sales people, the computer can find and arrange the electronic index cards any way you like. You want to know whether taking a graduate course in sales helps your people's performance? Just ask the data-base program to list each staffer by education and sales record.

Anyone who has placed a query like that and watched the results spin out neatly across the screen can tell you what a marvelous feeling of power and control it provides. The problem is that such control over information has not been easy to achieve on the existing major-league data-base programs. The industry's standard data base, Dbase III, includes a programming language that is about as easy to master as the Mahabarta dialect of ancient Sanskrit. That's why most offices have at best one or two people who know Dbase -- and everybody else is dependent on those two experts.

The Hypercard program Apple is going to build into all Macintosh computers takes maximum advantage of the standard Mac environment, which relies on pictures (what the Macophile purists call "icons") and simple, yes-or-no questions instead of complicated commands. Like the computer it is built for, Hypercard can handle information in several different forms -- not just words and numbers, but also graphs, pictures and sound.

One example Apple suggested for a Hypercard data base would be an electronic bird-watching notebook. Each entry could include information on the species, drawings of the bird, a map of its habitat, and even a digitalized recording of its call. Theoretically, an ornithologist could then use the Mac to compare different birds by call, by wing shape, or whatever.

Everybody ought to welcome Hypercard because, if the idea works, it will surely spread into the worlds of MS-DOS, PS/2 and other systems in a short time. The only place where Hypercard may not be welcome is in the corporate corridors of Ashton-Tate, makers of the mighty Dbase.

Ashton-Tate has been racing to get out its new Macintosh version of Dbase. But now Apple has stolen all the thunder with a built-in data base engine that may be even better.