Editor's Note: This page was updated February 3, 2004.

It's one of the hottest industries in America. Easier to order at home than a pizza, bigger than rock music, it's arguably the most profitable enterprise in cyberspace. AT&T has been in the business. Yahoo! has profited from it. Westin and Marriott have made more money selling it than selling snacks and drinks in their mini-bars. And with estimates as high as $10 billion a year, it boasts the kind of earnings that most American businesses would envy.

It's pornography. And with adult movies, magazines, retail stores, and the growth of the Internet, business is booming. But the leaders of the adult entertainment industry are worried. They viewed the election of George W. Bush and his appointment of Attorney General John Ashcroft as a signal that there is renewed interest in mounting obscenity prosecutions.

In "American Porn," FRONTLINE reports on the forces behind the explosion of sexually explicit material available in American society. Through interviews with adult entertainment executives and lawyers, porn producers and directors, federal and state prosecutors, anti-porn activists and a Wall Street analyst covering the entertainment industry, the program examines the business ties between respected corporations and porn companies, the rise of extreme hardcore porn, and the pending political battle that may soon engulf the multibillion-dollar pornography industry.

"American Porn" begins with an inside look at some of today's most successful pornography businesses -- from Larry Flynt Publications to the popular Internet site Danni's Hard Drive -- to see how their profits have exploded in the past few years. According to Flynt, his company -- a conglomerate of movies, strip clubs, sex emporiums (including the upscale Hustler Hollywood), and Internet sites -- is worth $400 million. Danni's Hard Drive proprietor Danni Ashe, a former exotic dancer turned dot-com millionaire and CEO, told FRONTLINE she expected to earn $8 million last year alone.

While most Americans decry the avalanche of sexually explicit material, the profits speak for themselves. FRONTLINE explores the range of pornography now available -- from soft porn "couples" entertainment to the most extreme of hardcore pornography -- and why large numbers of Americans are finding something alluring in the adult entertainment arena. Both Flynt and Ashe credit the 1990s explosion of adult material to the ease of viewing and ordering porn from the Internet. Equally important, they say, was the Clinton administration's relaxed attitude toward pornography. Some former Justice Department officials say that corporate America felt it was safe to enter the profitable porn market.

"Companies like AT&T bought up a cable company, signed contracts with the Hot Network, which is a hardcore pornographic site," says Patrick Trueman, former head of the Justice Department's obscenity section in the Reagan and Bush administrations. Trueman now represents the American Family Association, a nonprofit organization promoting traditional family values.

"Other mainstream companies thought, 'We can do this, too,'" he says. "And why not? There's a big market and no penalty."

Times are changing, however, and "American Porn" chronicles not only how porn has been prosecuted in the past -- but how it may soon be prosecuted again. With George W. Bush as president, porn moguls are nervous. In an attempt to head off a government crackdown, the top adult entertainment executives have created a list of 21 pornography no-no's. Dubbed the "Cambria List" after First Amendment attorney and porn industry defense counsel Paul Cambria, who was involved in the list's preparation, it warns porn producers against showing such acts as bestiality, urination, and facial ejaculation.

Some in the industry, such as Extreme Assocites producer Robert Zicari (known as "Rob Black" in the business), insist they will continue to test the limits despite the Cambria List. Zicari will get his chance. As of February 2004, he and his wife, Janet Romano, are awaiting trial on federal obscenity charges. It's the first time in more than a decade the federal government has filed such charges.

Other pornography producers are concerned that the very pioneers of the business are selling out in order to appear mainstream.

"It's a bunch of rich guys running scared," producer Mark Cromer tells FRONTLINE. "It's a bunch of guys who were, maybe, rebels in the 1970s and 1980s and don't want to fight anymore. They want to take their chips out of the bank and cash them in and go home and play golf."

But big pornographers aren't the only ones concerned. This FRONTLINE report looks at how mainstream companies have become wary as well. Yahoo!, for example, withdrew its bid to open a virtual sex shop following an anti-porn campaign waged by the American Family Association.

Will the big distributors of pornography -- such as cable and satellite operators -- also be affected by a government crackdown? Until now, companies such as AT&T have argued that they are like the postal service -- delivering material that people want and have ordered. They claim that they are meeting a popular demand and see nothing illegal or wrong in what they are doing. But will the U.S. Supreme Court arrive at new standards for obscenity that could challenge these assumptions?