Tonight marks the end of May sweeps and the conclusion of the 2005-2006 season. The night’s most heated competition is between the two-hour conclusion of “American Idol” (7 p.m., Fox) and the season finale of “Lost” (8 p.m., ABC), also running for two hours. A repeat clip retrospective of “Lost” (7 p.m.) precedes the finale.

“Lost” viewers have been promised a lot of answers. But before you get too excited, remember that last year’s finale simply opened the door to the hatch. And they’ve been pushing our buttons ever since. I’m gearing up for a boatload of new questions.

This season marks the second year in a row that network shows have continued to attract huge audiences, and some generated the kind of critical buzz and water-cooler conversation that once seemed to be the sole province of HBO.

Then there is “Idol.” Just a few years back, people predicted that no network show would ever be watched by 40 million to 50 million viewers per week. “Idol” proved them wrong.

I’ll venture two grand theories about the reasons for “Idol” mania. Let’s call them youth and democracy.

There is nothing more addictive than watching young, talented people doing their best. That’s why we love the Olympics. Television tends to stereotype young people as petulant, spoiled, oversexed, undereducated and rude. In contrast, most “Idol” finalists appear to be pleasant, hardworking, gracious and grateful for the experience. Television producers should take note. A show like “The Bedford Diaries,” featuring sex-obsessed, miserable teens, attracted fewer than 2 million viewers. “Idol” is watched by tens of millions. You do the math.

Democracy is another matter. “Idol” encourages and celebrates audience participation. That’s a subversive and exciting notion, given the arbitrary, often-closed world of stardom. Who, after all, dictated that Ashlee Simpson should become a household name?

With its millions of phone calls and text messages, “Idol” at least gives viewers the illusion that they have a choice and a voice. And what’s so bad about that? It’s the “American (Idol)” way.

Tonight’s other highlights

¢ A daytime talk-show host discusses drugs on “Escaping Addiction II” (7 p.m., CBS), hosted by Dr. Phil McGraw.

¢ Rival hairdressers join forces to raise cash in the 2004 comedy “Hair Show” (7 p.m., UPN).

¢ Ben Affleck and Jennifer Garner star in the 2003 action movie “Daredevil” (7 p.m., WB).

¢ Scheduled on “Dateline” (8 p.m., NBC): tracking predators.

¢ A winner emerges on “Top Chef” (9 p.m., Bravo).