She laid her leather jacket over a concrete slab, and she and Bill sat down, nuzzling. Then she looked into the camera and, very cordially, spoke: “I’m Claire Adams.” “And I’m Wild Bill.” “And welcome to a very special Men In Pain update.” Just like that, like the opener of some fireside holiday special. They interviewed each other. She asked if there was anything she shouldn’t do, any ground rules. “I don’t like my ears being slapped,” he said.

They started on an old stage in the armory gymnasium, rundown to the point of missing its floorboards entirely and gathering trash — a Coke case, a poster advertising youth boxing classes once held here — in the underpinnings. There, Wild Bill was tied to a column and flogged. (There are rarely story lines in Kink’s porn, and acting is discouraged.) His crotch was slapped. Later, in the boiler room, he would be kicked and suspended from the ceiling on his back, like a hairy spider. In between takes, after Wild Bill mentioned getting a little back pain, Adams would adjust the cat’s-cradle of ropes.

Even as child, Acworth told me, he liked seeing people bound. “I would get an erection while watching a cowboy-and-Indian movie where somebody was getting tied up,” he said, “which I didn’t really understand.” For a long time, he experimented by tying up himself, alone; he was shy and didn’t have a girlfriend until his 20s. It seemed natural that when starting Kink, he would gear his company toward the subculture around consensual sex play involving bondage, discipline, domination, submission and sadomasochism — the B.D.S.M. community. It was a way to indulge his own fetish but also a shrewd business decision. With a bondage site, Acworth told me, he knew what the customer wanted.

Initially, his instinct proved sound. But shortly after he moved to San Francisco to leap full time into the lavish free-for-all of online porn, Hogtied’s sales leveled off. Similar sites, often featuring the same licensed photographs, littered the Web. So Acworth started producing his own content in his spare bedroom. He would tether models to a homemade wooden scaffold, set up a tripod and film himself busily whipping, spanking and tickling them with various implements — all the while clicking still photos with a remote. He wore a black mask and called himself Peter Rogers in case he decided to abandon the stagnating business and return to Columbia.

The ways online porn was created, marketed and sold were beginning to be reinvented. Or, rather, they were finally being properly invented. Even by 1999, search engines like Yahoo were harder to outsmart, and Acworth’s tricks for getting Hogtied ranked highly no longer worked. He followed the lead of bigger porn sites, recruiting vast networks of “affiliates” to lure traffic to Kink’s sites with smartly placed ads, galleries of free samples, spam or other means. The industry’s first affiliates were hobbyists, amateur connoisseurs collecting their favorite online porn in galleries or directing others toward it in newsgroups. Today it’s a competitive industry in its own right, with self-employed, stay-at-home entrepreneurs using a variety of increasingly sophisticated advertising tools. Companies like Kink or Naughty America — another prominent suite of porn sites with far more conventional content (errant secretaries, hair-twirling co-eds) — now work with invisible sales forces of tens of thousands of affiliates.

But in those early years, with credit-card numbers circulating among unscrupulous Web masters and affiliates, various frauds proliferated. Prime among them was “credit-card banging,” whereby a person subscribing to one site might find he has been charged for a slew of others. For their part, customers found that they could easily repudiate charges they had authorized; Internet porn involved no physical delivery, and card companies, apt to take the nice suburban husband’s word over the pornographer’s, frequently issued chargebacks.

Such headaches were not limited to porn. But porn was one of the few things being rampantly bought and sold online, and the financial sector, which hadn’t yet worked out a viable system for e-commerce, scrambled to develop one on the fly. Many banks and credit-card companies, including American Express, refused to deal with porn; others steadily introduced stiffer regulations and fees for high-risk industries. A site with more than 2.5 percent of its purchases charged back could be subject to closer oversight and penalties; eventually, its merchant account, and thus its ability to process credit cards, might be revoked. Soon, the standard allowable chargeback ratio lowered to 1 percent. Third-party billing companies stepped in to process the charges through their own merchant accounts, but they routinely take 15 percent or more of each transaction. (Paypal, which charged as little as 2.9 percent, ceased dealing with porn in 2002.) For the typical, sloppy amateur — the lackluster guy with a digital camera and some lady friends — billing suddenly became a nightmare. “And without billing, it just don’t work,” says Gary Kremen, who founded both the porn site Sex.com and the dating site Match.com in the mid-’90s. “Because what are you going to do, send money in the mail?”