It was the beginning of a beautiful – often competitive, always entertaining – friendship.

Twenty-four years ago, on Nov. 24, 1978, David Letterman made his first appearance with Johnny Carson on “The Tonight Show.” It would be one of 22 guest shots on the broadcast, and that’s not counting the 50 times Dave sat in for Carson as guest host.

Letterman wasn’t new to TV in 1978. He had moved to Los Angeles in 1975 from Indiana, where he’d been a TV weatherman and host of a children’s show. His first network break was on the CBS variety series “Mary,” starring Mary Tyler Moore. But it was his exposure on “Tonight,” combined with his acerbic comic wit and endearing dental work, that gained him national attention.

Two years after debuting with Carson, Letterman inaugurated a morning comedy-variety program, “The David Letterman Show.” It ran only three months on NBC, but it was clear that Letterman was redefining the role of the talk-show host, much as Carson had almost two decades earlier.

“Late Night With David Letterman” premiered on NBC in February 1982. Throughout its 11 years, “Late Night” was honored with five Emmys and 40 Emmy nominations. In 1992, Letterman received the prestigious George Foster Peabody Award for taking “one of TV’s most conventional and least inventive forms – the talk show – and infusing it with freshness and imagination.”

In 1993, Letterman and Carson made news again: Carson retired, and Letterman was only second choice to replace him, one-upped by Jay Leno. Letterman subsequently jumped the NBC ship and aligned with CBS to launch “Late Show With David Letterman.”