"American Idol" began as a ragged outsider — a summer show with a harsh Brit judging sweet-faced Americans.

Now, 4 1/2 years later, it's the ultimate insider. It can transform TV seasons and create music careers.

It's ready to do it again, beginning tonight.

Each season, the contestants seem a little different. "It felt slightly more naive to me this time," Simon Cowell, the show's most acerbic judge, says of the auditions. "There were more young contestants. I'm talking about 16 to 18 years old."

That naivete could be because the show had some new tryout cities, including Greensboro, N.C., Cowell figures. Then again, young contestants could have felt encouraged by the recent winners.

When Fantasia Barrino won in 2004, she was 19 and illiterate. When Carrie Underwood won in 2005, she was 22 and near her college graduation, but still wide-eyed. Before the competition, she had never been on a plane and had rarely left Oklahoma.

Barrino tended to talk back when Cowell criticized her. "I encourage it," he says. "You're entitled to say what's on your mind."

Underwood, like most contestants, absorbed the verbal blows quietly. "I would be fine with it if it was in private," she says. "But knowing that all my friends and family were watching — that was hard."

She survived, won and recently blitzed country radio and holiday TV. Her new album is "Some Hearts."

And her success has expanded the show. "We've got more country singers, including male country singers, this year," Cowell says.

Guys have always been a tricky matter for "Idol." In 2004, judges admitted it was a weak male field. In 2005, they claimed it was a better lineup.

Now Cowell reverses that. "I was never crazy about the guys," he says. "Just Bo."

That's Bo Bice, a rocker who has just released his new CD "The Real Thing," which is climbing the charts.

He had lost to Underwood in the finale. "American Idol" is like that, with contestants pulling surprises.