Three had come all the way from the San Francisco Bay area, one from Miami. Two lived less than 60 miles away, in Newark and Elizabeth, N.J. and two even closer, in Brooklyn.

All eight were arrested on prostitution charges here, snared in a new sting operation by the Nassau County police that focuses on Craigslist.org, the ubiquitous Web site best known for its employment and for-sale advertisements but which law enforcement officials say is increasingly also used to trade sex for money.

Nassau County has made more than 70 arrests since it began focusing on Craigslist last year, one of numerous crackdowns by vice squads from Hawaii to New Hampshire that have lately been monitoring the Web site closely, sometimes placing decoy ads to catch would-be customers.

“Craigslist has become the high-tech 42nd Street, where much of the solicitation takes place now,” said Richard McGuire, Nassau’s assistant chief of detectives. “Technology has worked its way into every profession, including the oldest.”

Augmenting traditional surveillance of street walkers, massage parlors, brothels and escort services, investigators are now hunching over computer screens to scroll through provocative cyber-ads in search of solicitors.

In July raids, the sheriff of Cook County, Ill., rounded up 43 women working on the streets — and 60 who advertised on Craigslist. In Seattle, a covert police ad on Craigslist in November resulted in the arrests of 71 men, including a bank officer, a construction worker and a surgeon.

And in Jacksonville, Fla., a single ad the police posted for three days in August netted 33 men, among them a teacher and a firefighter. “We got hundreds and hundreds and hundreds of hits” in phone calls and e-mail messages, said John P. Hartley, the assistant chief sheriff there.

Sex and the Internet have been intertwined almost since the first Web site, but the authorities say that prostitution is flourishing online as never before. And while prostitutes also advertise on other sites, the police here and across the country say Craigslist is by far the favorite. On one recent day, for example, some 9,000 listings were added to the site’s “Erotic Services” category in the New York region alone: Most offered massage and escorts, often hinting at more.

Law enforcement officials have accused Craigslist of enabling prostitution. But the company’s president, Jim Buckmaster, said its 24-member staff cannot patrol the multitude of constantly changing listings — some 20 million per month — and counts on viewers to flag objectionable ads, which are promptly removed.

“We do not want illegal activity on the site,” he said. Asked whether the company supported the police’s placing decoy ads on Craigslist, Mr. Buckmaster said: “We don’t comment on the specifics” of law enforcement.

The police have also occasionally turned to Craigslist to trace stolen goods offered for sale or make drug arrests. In June, in Nassau, spotting code words like “snow” or “skiing” to refer to cocaine, they set up a sting with an undercover officer to arrest a man who advertised cocaine for sex.

While Mr. Buckmaster said Craigslist was no different from old-media publications that have long carried sex-oriented ads, law enforcement officials say its scope and format are especially useful to the sex industry. With listings for some 450 cities around the world, Craigslist claims to have 25 million users and 8 billion page views a month. Posting advertisements, except those in the employment and some housing categories, is free, as is responding to them by e-mail. “The Internet has allowed people to make contact in a way not possible before,” said Ronald Weitzer, a sociology professor at George Washington University and a researcher on prostitution. “Ten years ago this was not happening at all.”

As Nassau’s district attorney, Kathleen Rice, said of Craigslist: “It’s as easy as it gets.”

Tracy Quan, a member of the advocacy group Prostitutes of New York and author of the autobiographical novel “Diary of a Married Call Girl” (Harper Perennial, 2006), acknowledged that “the Internet became a virtual street for people in the sex industry,” but said that “the police are as inventive and as wily as sex workers are.” She said that the stings amounted to entrapment of consenting adults, and that “it seems like an enormous waste of time resources by authoritarian busybodies.”

The police say that Craigslist has changed prostitution’s patterns, with people roaming the country, setting up shop for a week or two in hotels — often near airports — where they use laptop computers and cellphones to arrange encounters for hundreds of dollars, then moving on to their next location.

“They like to move around, that’s for sure,” said Assistant Chief McGuire. “They’re flying in from out of state because there is money here” on Long Island.

In Westchester County this spring, the police in Greenburgh, Rye, Rye Brook and Elmsford formed a joint task force to investigate ads on Craigslist, resulting in 30 arrests. Some of those arrested were out-of-town prostitutes who booked numerous dates in advance, then whisked in for a busy couple of days, the police said.

Amid the police crackdown, in a game of electronic cat-and-mouse, the authorities say that Web site users who get wind of enforcement sometimes post warnings to thwart investigators. The Craigslist modus operandi provides mobility, helping prostitutes keep a few steps ahead of the law, law enforcement officials say. It also affords a degree of anonymity — if they are caught, being away from home makes an arrest less embarrassing.

Law enforcement officials ask why Craigslist even includes Erotic Services among its 191 categories. Mr. Buckmaster, the company president, said the site created that category “at the request of our users” for legitimate massage, escorts and exotic dancers. In an e-mail interview, he said that the police had praised the company’s cooperation, though he did not give examples. Despite police complaints that Craigslist facilitates prostitution, some experts say the Web site also aids enforcement.

“Craigslist is a very open site, and it leaves digital footprints,” said Leslie A. Harris, president of the nonprofit Center for Democracy and Technology. “It makes it easier for the police.”

My Opinion – It just seems to me that it’s time the government got out of the way between two consenting adults unless there are drugs or guns involved. To target the provider but not the customer is only creating a an oppressed group where one needn’t exist.

There are all sorts of explanations for the reasons for the sharp rise. More and more ads on television and billboards are sexually inspired, there is increased ability to explore sexuality on the internet and the increasing divorce rate and lowering marrige rate means more men are without a regular sex partner.

In addition to all these reasons, I think the internet has changed how we perceive sex and sexuality – especially our own. I remember the first time I tripped over a site about bondage and sado-masochism. Woo! I always thought I was a hot number in the sack but I quickly learned how plain vanilla I really was!

Today we’re almost forced to discuss sex with our children because they bump into it so often in TV ads, movies and surfing the net. Back in my day we were lucky if our mothers explained menstruation much less the mechanics of sex!

Personally I see nothing wrong with prostitution as long as safety takes priority. It’s legal where I live as long as it’s inside a building and the women take their health seriously. If a woman wants to sell it and a man wants to buy it, it’s really none of my business. I know I’ll get complaints about the victimization of women but wouldn’t we be better off talking about why women can make so much more money on their backs than checking out groceries?

Sex psychologist Dr Lesley Perman-Kerr says, “People are more overloaded with work and feel they don’t have time to form relationships but still want to have sex. Money isn’t the object but the desire to form a relationship with someone is not there. And the internet has made it more available.”

Both men and women are saying they want the sex life they want and they’re not prepared to settle for anything less. Because the option of hiring a prostitute for women is rather difficult, most women opt for a casual sex affair with one man. Men use prostitutes because it can be quick, reasonably priced and there are no strings attached.

A friend of mine who admits to using prostitutes on a regular basis says it’s not about paying for sex. He says he could get sex whenever he wanted it but chooses to use prostitutes because of the no strings aspect. He says, “I don’t pay them for sex, I pay them to leave immediately afterwards and I don’t have to call them in the morning.”