Johnny Carson's "Tonight" show was a national habit, and the comedian's unprecedented 30-year run as host was considered a show business "freak accident" that may never be repeated.

At its peak, "Tonight" on NBC TV reached more than 14 million people five times a week and, on his final show which Carson did alone on May 22, 1992, an estimated 55 million watchers tuned in.

NBC reported that Carson died early Sunday of emphysema at his home in Malibu, Calif. He was 79, reports UPI.

A witty, charming and unpredictable man on camera, Carson tended to be aloof if courteous in person.

Carson took over as host on "Tonight" on Oct 1, 1962, succeeding Jack Paar. He got the job after many others including Jackie Gleason and Groucho Marx turned it down.

By 1967, Carson was an "institution," and so-labelled by a Time magazine cover story that year. His popularity did not diminish and Carson's phenomenal success during a quarter century has been attributed to his comic charm and ability to make guests and audiences alike feel comfortable.

Among budding celebrities who got a boost from appearances on his show were Barbra Streisand, Bill Cosby, Flip Wilson and Joan Rivers.

Carson was sensitive to criticism that his guests and his monologues lacked depth or seriousness.

But he steered away from politicians and controversy.

"My job is to entertain people, not to attack a guest's point of view," he once said. "And I don't like to intellectualise on social issues. If you can make people laugh it's as important as making them aware of the prison situation in the United States."

What made Carson's show a nightly must-see, was not his interviews, but his opening monologue. For years, Carson's comedy took on events of the day that had been a reliable barometer of the public's mood.

When he began making jokes about Nixon's duplicity during Watergate, by all intents and purposes, Nixon's fate was sealed.

Carson was born Oct 23, 1925, in Corning, Iowa. His father was a lineman for an electricity company. The family moved a number of times until they settled when Johnny was eight years old in Norfolk, Neb.

He graduated from Norfolk high school in 1943 and enrolled in the Navy's V-12 programme, attending midshipman's school at Columbia University and serving aboard the battleship Pennsylvania in the Pacific.

When he quit the "Tonight" show in 1992, television observers commented that the phenomenon of one person lasting as long as Carson, would never be repeated.

Viewed more as a show business "freak accident," Carson's longevity was also attributed to the showman's almost flawless pacing his ability to perform almost every night of the week, but to pace himself so that he was never overexposed.