Along with the freest access to knowledge the world has ever seen comes a staggering amount of untruth, from imagined threats on health care to too-easy-to-be-true ways to earn money by forwarding an e-mail message to 10 friends. "A cesspool," Google's chief executive, Eric E. Schmidt, once called it.

David and Barbara Mikkelson are among those trying to clean the cesspool. The unassuming California couple run Snopes, one of the most popular fact-checking destinations on the Web.

For well over a decade they have acted as arbiters in the Age of Misinformation by answering the central question posed by every chain letter — is this true? — complete with links to further research.

The popularity of Snopes — it attracts seven million to eight million unique visitors in an average month — puts the couple in a unique position to evaluate digital society's attitudes toward accuracy.

After 14 years, they seem to have concluded that people are rather cavalier about the facts.

In a given week, Snopes tries to set the record straight on everything from political smears to old wives' tales. No, Kenya did not erect a sign welcoming people to the "birthplace of Barack Obama." No, Wal-Mart did not authorize illegal immigration raids at its stores. No, the Olive Garden restaurant chain did not hand out $500 gift cards to online fans.

The Mikkelsons talk matter-of-factly about why these stories spread the way they do.

"Rumors are a great source of comfort for people," Mrs. Mikkelson said.

Snopes is one of a small handful of sites in the fact-checking business. Brooks Jackson, the director of one of the others, the politically oriented FactCheck.org, believes news organizations should be doing more of it.

"The 'news' that is not fit to print gets through to people anyway these days, through 24-hour cable gasbags, partisan talk radio hosts and chain e-mails, blogs and Web sites such as WorldNetDaily or Daily Kos," he said in an e-mail message. "What readers need now, we find, are honest referees who can help ordinary readers sort out fact from fiction."

Even the White House now cites fact-checking sites: it has circulated links and explanations by PolitiFact.com, a project of The St. Petersburg Times that won a Pulitzer Prize last year for national reporting.

The Mikkelsons did not set out to fact-check the Web's political smears and screeds. The site was started in 1996 as an online encyclopedia of myths and urban legends, building off the couple's hobby. They had met years earlier on a discussion board about urban legends.

Mr. Mikkelson was a dogged researcher of folklore. When he needed to mail letters requesting information, he would use the letterhead of the San Fernando Valley Folklore Society, an official-sounding organization he dreamed up. They would investigate the origins of classic tall tales, like the legend of the killer with a prosthetic hook who stalked Lovers' Lane, for a small but devoted online audience.

After the Sept. 11 terrorist attacks, users overwhelmed the Mikkelsons with forwarded e-mail claims and editorials about the culprits and the failures of the government to halt the plot, and the couple reluctantly accepted a larger role. They still maintain a thorough list of what they call "Rumors of War."

Less than a year later, Snopes became the family's full-time job. Advertisements sold by a third-party network cover the $3,000-a-month bandwidth bills, with enough left over for the Mikkelsons to make a living — "despite rumors that we're paid by, depending on your choice, the Democratic National Committee or the Republican National Committee," Mr. Mikkelson said.

Much of the site's resources are spent on investigating political claims, even though the Mikkelsons say politics is the last subject they want to write about. (Barbara cannot even vote in American elections; she is a Canadian citizen.) Claims relating to President Obama are now the top searches on the site but "even when there were Republicans in the White House, the mail was still overwhelmingly anti-liberal," Mr. Mikkelson said.

In late August, Mr. Mikkelson studied an e-mail chain letter titled "The Last of the Kennedy Dynasty" purporting to explain why the late Senator Edward M. Kennedy was unfit for acclaim. Some of its 10 bullet points were true (yes, Mr. Kennedy was cited for reckless driving while in college), but others were misleading assumptions (no, his accomplishments were not "scant").

Mrs. Mikkelson rolled her eyes at her husband's plans to fact-check the chain letter. "That's ephemera," she said.

He agreed, but the Kennedy report wound up being the Web site's most-searched subject the next weekend.

The Mikkelsons employ two others full time to manage the enormous volume of e-mail to the site. Increasingly, curious readers are sending videos and photos as well as e-mail, requiring even more investigation. They publish on average one new article each day.

The enduring articles are the ones about everyday fears: computer viruses, scams, missing children. Some e-mail chain letters, like the one offering users $245 for forwarding the message, never fade away.

"People keep falling for the same kind of things over and over again," Mr. Mikkelson said. Some readers always seem to think, for instance, that the government is trying to poison them: Mrs. Mikkelson said rumors about AIDS have been recycled into rumors about swine flu vaccines.

For the Mikkelsons, the site affirms what cultural critics have bemoaned for years: the rejection of nuance and facts that run contrary to one's point of view.

"Especially in politics, most everything has infinite shades of gray to it, but people just want things to be true or false," Mr. Mikkelson said. "In the larger sense, it's people wanting confirmation of their world view."

The couple say they receive grateful messages from teachers regularly, and an award from a media literacy association sits atop the TV set in Mr. Mikkelson's home office.

It is not just the naïveté of Web users that worries the "Snopesters," a name for the Web site's fans and volunteers. It is also what Mr. Mikkelson calls "a trend toward the opposite approach, hyper-skepticism."

"People get an e-mail or a photograph and they spot one little thing that doesn't look right, and they declare the whole thing fake," he said. "That's just as bad as being gullible in a lot of senses."

But even though Snopes pays the bills for the couple now, through advertising revenue, they doubt they are having much of an impact.

"It's not like, 'Well, we have to get out there and defend the truth,' " Mrs. Mikkelson added. "When you're looking at truth versus gossip, truth doesn't stand a chance."