The supercomputer, dubbed Watson, owes that significance to its ability to deliver more than calculations and documents. It can answer verbal questions posed by humans.

That ability, says IBM researchers and industry analysts, makes this machine more equipped than any before it to organize "thoughts" and verbally converse with people.

"I would say it's the largest computing advance of this century," said Richard Doherty, research director at Envisioneering Group. "I've been in computing since 1973 and followed technology before that, and this is the largest advancement in decades. This isn't an iPad. To reach [a computer] conversationally and have it respond with knowledgeable answers is a sea change in computing."

Watson's first appearance on the long-running Jeopardy game show aired the first episode of its man-vs-machine competition last night. Watson faced two Jeopardy champions - Brat Rutter and Ken Jennings.

Half of the first game aired Monday night, and Watson and Rutter tied for the top spot with $5,000. Jennings finished the day in third place with $2,000.