For all of the dramas, comedies, documentaries, music, news, talk and sports available on television, it’s easy to get confused about the essential nature of television. It is an advertising medium. And when companies find other, better ways to sell their products, television as we know it will begin to change, or vanish, or a little bit of both.

Nobody symbolizes the marriage of television, gimmickry and salesmanship better than Ron Popeil, the subject of tonight’s “Biography” (7 p.m., Biography Channel).

Even if you don’t know the name Ron Popeil, you probably recognize, or own, one of his many Ronco products and inventions, sold via TV commercials and infomercials during the past five decades. Who doesn’t remember his famous Pocket Fisherman, the Veg-O-Matic, the Smokeless Ashtray, the Miracle Broom and the Inside-the-Shell Egg Scrambler?

“Biography” traces Popeil’s roots to a family of successful pitchmen who sold wares out of peddlers’ carts at boardwalks and county fairs. Popeil’s father was a noted salesman and inventor who, we learn, gave him everything he needed but love. “Biography” also chronicles his many marriages, his brief bankruptcy and other stumbles on the way to marketing Nirvana.

Ronco products even worked their way into a classic episode of “The Simpsons,” when Homer bought the voice-throwing Mr. Microphone, later used by Bart to convinced townsfolks that he was Timmy O’Toole, a boy trapped in a well.

But wait, there’s more …

Popeil recently sold his company to spend time raising his two young daughters, but not before Ronco’s greatest triumph. The Showtime Rotisserie, marketed via infomercial, has sold more than 3 million units. Now retired, Popeil is trying to develop a way to replace those dangerous hot-oil turkey broilers with something safe and easy to use. He promises you’ll be able to insert the bird and “set it — and forget it!”

¢ The “Wide Angle” (8 p.m., PBS, check local listings) documentary “1-800 India” looks at outsourcing from the perspective of the Indians who work at a huge telephone call center.

Tonight’s other highlights

¢ Shaun Robinson and Damien Fahey host “Miss Teen USA 2006” (7 p.m., NBC).

¢ On back-to-back episodes of “House” (Fox), a laughing policeman (7 p.m.), Foreman faces morality (8 p.m.).

¢ On back-to-back episodes of “Veronica Mars” (UPN), justice for Felix (7 p.m.), nightmares (8 p.m.).

¢ On back-to-back episodes of “Gilmore Girls” (WB), wedding plans (7 p.m.), woman’s best friend (8 p.m.).

¢ Scheduled on “48 Hours Mystery” (9 p.m.): The FBI unravels the case of a missing coed after 10 years.

¢ A hefty posse take on a prodigy on “Law & Order: Special Victims Unit” (9 p.m., NBC).

¢ “Primetime” (9 p.m., ABC) looks at outsiders and people with unusual jobs.

¢ “REAL Sports with Bryant Gumbel” (9 p.m., HBO) includes an interview with NBC executive Dick Ebersol.

¢ Tommy’s dad goes missing on “Rescue Me” (9 p.m., FX).