With all the talk these days about the Internet -- that vast network of computers that links millions of people around the world -- one of the most frequent questions I get is, "How do I get on?"

The answer is: With some difficultly.

Unless you're affiliated with a university or a large corporation that maintains a dedicated Internet link, you're going to have to find an on-ramp to the "information highway." When you do find one, there will undoubtedly be a toll booth at the entrance. And once you're on the road, given the state of today's software, you'd better be prepared for flat tires, broken transmissions and radiator boil-overs.

Those disclaimers aside, the journey can be a rewarding one. There's an incredible amount of information out there, not to mention a direct link to 23 million Internet users around the world.

Before you decide to make the trip, it's a good idea to learn a little bit about what the Internet is and isn't. You may also be able to take a shortcut that can save you time and money. In this column and the next, I'll talk about Internet basics.

First things first. The Internet is not Prodigy or CompuServe or America Online. These companies are complete, self-contained information services. For a fee, they provide you with a well-organized universe of electronic mail, news, weather, features, discussion groups, information databases and collections of programs, graphics and other files to download. They also provide friendly, dedicated communications software that makes their offerings easy to navigate.

With any of these large providers, you have a standard business-to-customer relationship. They have to keep you satisfied, ensure that the quality of information they deliver is good, and make the service attractive in order to keep your business. You have every right to demand good service in return for your money (It doesn't always work out that way, but that's the theory).

The Internet, by way of contrast, is a huge, worldwide network of networks of individual computer systems run by universities and corporations, largely to enhance their own research and development efforts. These institutions have agreed to share their resources with users on other systems.

The Internet as a whole also provides a vehicle for sending and receiving electronic mail, and that's how most people use it. E-mail capability also has given rise to thousands of special interest "mailing lists" and "news groups" that have made the Net an electronic meeting place for millions of people.

Linked by high-speed phone lines, the Internet spreads in all directions, and it's growing every day. There's no plan, no overview. Other than a committee that sets technical standards and maintains the system's high-speed, fiber-optic backbone, nobody runs the Internet. Each organization is responsible for its own computer system, and the people who run those systems are responsible to their organizations. In fact, many of the archives and databases that make the Internet so interesting are maintained by volunteers who devote a great deal of their free time to them.

Some computer systems on the net are virtually closed, allowing little access other than E-mail. Others put out the welcome mat, allowing users on other systems to share their wealth. For example, most large university and public library systems make their card catalogs, periodical indexes and archives of scholarly and research papers available on the Net. There are interesting databases everywhere -- you can find libraries of computer programs, the complete works of Shakespeare, on-line magazines, collections of NASA space photographs, electronic comic books, compilations of Bill Clinton's speeches -- almost anything that someone had a mind to store and catalog.

Each system on the Net also has its own look and feel. Some provide nothing more than a cryptic prompt, and users have to memorize dozens of the unintelligible commands that have made the Unix operating system so beloved for years. Others welcome you with GOPHER, a friendly menu-based system named for the University of Minnesota programmers who developed it. Still others provide sophisticated World Wide Web and Mosaic servers designed to work with special PC-based programs that treat the Internet as a gigantic hypertext document. These systems point the way to the future, but they're still in their infancy.

Given this anarchy, there's is no such thing as an "Internet Manual," which is one of the reasons that half the books crossing my desk for review these days bill themselves as Internet manuals. The problem is that by the time they're in print, they're often out of date. As a result, getting around the Internet can be either an exercise in frustration or a marvelous if somewhat quirky adventure, depending on your state of mind.

If you're not affiliated with a university or company that maintains an Internet link with dial-in capability, you'll have to set up an account with an Internet service provider. These are companies that maintain computers linked to the Internet. They make their money by providing you with a way to dial in with a modem and make connections with other systems. They also give you an electronic mailbox through which others can reach you.

Most of these Internet providers are local or regional. The Boston-based DELPHI service is available nationally through local calls in most metropolitan areas, and a few, like Cerfnet, provide access through an 800 number -- at a stiff price. Almost all can be accessed with standard communications programs. Some providers can set up more expensive SLIP (Serial Line Internet Protocol) connections that require special software but make Internet access easier and more secure.

If your communications experience is limited to Prodigy and America Online -- with their friendly, no-brainer start-up kits, you'll be in for a rude shock. Some Internet providers may offer basic menu services to help you navigate a bit, but basically, all you're buying is access to the highway.

Once you're in, you're on your own, and when you do log onto other systems, you're there as a guest. These folks don't get anything for allowing you to get your foot in the door, and you may find that systems you're looking for are unavailable because they've been taken off line for maintenance, changes or repairs. That's life on the Net.

Next time we'll discuss some of these options in detail, along with some easy and inexpensive alternatives.

Michael J. Himowitz is a staff writer for The Baltimore Sun.