David Denby isn't a prude. The film critic and author likes "incessant profanity," "trash talk" and "any kind of satire."

But he hates snark, the kind of "snarking insult" or bullying ridicule rampant in today's world, especially on the Internet.

Snark practitioners, according to Denby's new book, "Snark: It's Mean, It's Personal and It's Ruining Our Conversation" (Simon & Schuster), include the media Web site Gawker, celebrity blogger Perez Hilton and New York Times op-ed columnist Maureen Dowd, who gets her own chapter.

Denby, in a phone interview, defines snark as "the knowing nasty tone, the cheap shot." He writes that this staple of high school life is "spreading like pinkeye. In a media society, snark is an easy way of seeming smart."

Even mainstream media are embracing snark. "Baby Boomers want to stay young forever. The worst thing is to be seen as out of it. And old media is terrified of losing its audience," says Denby, 65, film critic for The New Yorker and author of "Great Books" and "American Sucker."

So what's wrong with snark?

"It's a critique of style, it's about grace and acting in classier ways," Denby says. "I want people to write better and read better and look at better movies."

The problem, he says, is that "snark cheapens talent into celebrity. It's only interested in personality and gossip."

What Denby calls snark, Perez Hilton, 30, calls honesty. A blogger since 2004 and author of "Red Carpet Suicide: A Survival Guide on Keeping Up With the Hiltons" (Celebra), Hilton says he "couldn't care less" that Denby describes his Web site, perezhilton.com, as "coarse, invasive, obsessional."

"To me, snark is a word predominantly used by snobby people," Hilton says, "and I don't consider myself snobby."