Free university-level courses suddenly are available around the world at the click of a mouse, thanks to MOOCs (massive open online courses). Some experts think this snowballing trend someday may offer inexpensive college education to millions.

Coursera -- an alliance of Princeton, Stanford, Duke and 31 other universities -- now presents 200 free classes to anyone who signs up via computer. Similar free choices are offered by edX, a joint venture of Harvard and MIT, plus Udacity and other high-tech operations.

Already, the University of Texas and Colorado State University award credits to some students who pass MOOCs. Last week, Coursera announced that the American Council on Education will evaluate five courses for possible university credit. To get recognized grades, students would pay "modest fees."

In the mushrooming computer age, the ability of anyone to attend college, on home terminals in spare hours -- at a tiny fraction of regular cost -- could be a blessing to millions of families. Schools everywhere are watching the fast-moving phenomenon. Most cannot yet figure how to earn revenue from the free instruction.

The effort rose to attention last year when Stanford professor Sebastian Thrun offered an artificial-intelligence course, and was swamped by 160,000 students in 190 nations. Grading their on-screen tests and papers was impossible, so Dr. Thrun let teams of fellow students grade each other.

A New York Times report said: "Professors delight in reaching more students in one course than they could otherwise teach in a lifetime."

Princeton sociologist Mitchell Duneire was amazed by his on-line sway: "Within three weeks, I had more feedback on my sociological ideas than I'd had in my whole teaching career."

Universities probably had no choice but to offer no-cost courses, because other providers -- such as the nonprofit Khan Academy on YouTube -- were presenting thousands of lessons to millions of students.

Computers are changing nearly every aspect of modern life. Eventually, they may alter the way Americans attend college.