Think of the things in life that are always ready. They need no warm-up time. It isn’t necessary to boot them up. Then, consider the opposite. What if you had to start up your pen? You might use it when an essay was due, but signing a check would be a big inconvenience. If using the phone required advance notice, you might place most of your calls to your parents on Mothers and Fathers Days.

In other words, the readiness of everyday things defines their utility in important ways. We use an oven on purpose, a refrigerator on demand. Boiling water for tea is different from getting a cold beer.

The immediacy of popping a beer can’s top is finally coming to the world of computing. It’s called always-on. And it will change fundamentally how you relate to your computers.

Simply put, always-on means your computer is connected to the Internet 24 hours a day, seven days a week, with no effort on your part. No modems, no dialing, no sitting down for an Internet session. The 30 seconds of beeps and whistles that accompany a dial-up session elevate the Net to something you approach with deliberation, when you have the time and energy to browse or chat. When you’re always-on, you will become a full-fledged member of the Net, instead of a drop-in caller. With always-on, cyberspace and the real world will suddenly overlap. Network access will be spontaneous. Call it instant Internet. Just add hot water.

With always-on, you will use the Net episodically, the way you might check a movie listing in the newspaper or grab a Coke and cookie. Not single-mindedly, but in the course of doing something else. Suddenly, the Internet will become part of your daily life. You can check if the plane is delayed as you put your coat on to leave the house, verify the recipe while you cook, solve a Scrabble question during the game, or defrost dinner from your car phone. And you can let information creep into your home without the shout of a telephone bell. A network that is ever-present, ever-available begs to be consulted and demands little in return.

Always-on also will change the way we work. For some perspective, let’s go back to 1981, when, at a brainstorming session to set a research agenda, a group of us listed using computers for interpersonal communication as a goal. The hope was for a machine that was as useful as a blackboard. We all had experience with thinking through a knotty issue as a team, each grabbing the chalk from the other as if to say, “Wait! Try this.” But we listed interpersonal communication as a distant dream back in 1981. We had no machines that could become part of our debate and join our creative process, and we saw no easy way of developing them. With always-on, those capabilities will suddenly be available to everyone. It will be easy to share documents or just, while talking on the phone with someone, to consult the Web and answer a question or make a point.

Always-on will be the way that traditional businesses—those that make real products, as opposed to computer-related products—enter the digital age. The reason is that it’s not just personal computers that can be constantly connected to the Internet. With computer chips getting cheaper and more powerful all the time, they will increasingly be imbedded in traditional products, and those products, too, will be always-on. (This is the goal of almost anyone who has used a computer in the past 20 years. We always knew the real revolution came when the computer became an invisible part of daily life.)

To understand how imbedded computers will create opportunities for traditional businesses, you need only to play a simple game: Name two companies, and then invent an imbedded computer that brings their diverse business lines into convergence. For example:

 Columbia/HCA Healthcare and Spode: dinnerware that measures fat intake.

 Georgia-Pacific and Cisco: smart wood that calls the vet when the horse stall smells bad.

 Lego and ADT: a toy R2D2 that wanders around the house looking for mice and burglars.

 Makers of kitchen equipment and National Geographic: a spice rack where each spice brings up the Web page of its country of origin when you place it on the counter. (This spice rack actually exists at MIT.)

To imagine how business will change, you might also consider how a company could own a corner of your mental real estate, the place in your brain that you reserve for some product or service. For example:

 Is Kodak a purveyor of film, or the answer to any question you may have about images—from where to find that Civil War photo to how you can remove the acne from your high-school daughter’s yearbook photo?

 Is Merrill Lynch an investment adviser, or the way your family learns about money?

 Is General Motors just a vehicle company or also a rolling ATM and credit card?

Once you get your head around the idea of always-on, you can start pondering the next big change that will come along. As the Net moves off the desk and into the objects that surround us, we can start to think about how the world will change when our Internet connection can travel around with us. In other words, how computing can go beyond always-on and become always-there.

Lippman is associate director of the MIT Media Lab. He can be reached at lip@mit.edu.