Erowid seeks to be a reference for everyone from the village stoner to the drug czar. Photograph by Andrew B. Myers for The New Yorker / Hand Lettering by Mousecake

You can’t tell a great deal about the Web site Erowid from its home page. A tagline reads, “Documenting the Complex Relationship Between Humans & Psychoactives.” This text is surrounded by photographs: a cactus, a cannabis bud, a bottle of ketamine, tabs of LSD. The design looks old, Web 1.0 old, with a simple typeface and a black background. The Tolkienesque name, the F.A.Q. page reveals, was coined with assistance from a dictionary of Indo-European roots. It means, roughly, “earth wisdom.”

People who are interested in psychoactive cacti, ketamine, and LSD are generally unfazed by strangeness. Any such person will likely know of Erowid, as will most toxicologists and many E.R. doctors. When the site launched, in 1995, it served as a repository of drug-culture esoterica, drawing just a few hits a day. Today, Erowid contains highly detailed profiles of more than three hundred and fifty psychoactive substances, from caffeine to methamphetamine. Last year, the site had at least seventeen million unique visitors.

In October, on the twentieth anniversary of Erowid’s launch, I travelled to the home of its founders, in the Gold Country of northeast California, where the Central Valley gives way to the Sierra Nevada and road signs along I-80 start marking the altitude. The hills are dotted with Gold Rush museums and monuments, along with evidence of a thriving cannabis-growing scene. Local television weathermen refer to the region as the Mother Lode.

The founders of Erowid are a couple in their mid-forties—a man and a woman who call themselves Earth and Fire, respectively. Their names date from 1994, when, as recent college graduates living in the San Francisco Bay Area, they went to a Menlo Park storefront to sign up for a dial-up account and for their first e-mail addresses: earth@best.com and fire@best.com. They live and work in a one-bedroom post-and-beam cabin, built in 1985 and surrounded by ten acres of forested land, on a high slope facing a ravine. The property’s original owner was a collector of obsolete industrial machinery, and the house is a collage of California artifacts, including oak floorboards salvaged from nineteenth-century Southern Pacific Railroad boxcars. During my visit, Earth, who is tall and lumbering and wears his hair in a ponytail, identified strains of a Grateful Dead track wafting from the home of a distant neighbor. Fire, who is more assertive and fast-spoken than Earth, has dark hair and fine features that often earn her comparisons to Björk.

On Erowid, which is run by Earth and Fire with the help of two off-site staffers and many volunteers, you can read about drum circles in the “Mind & Spirit” section, and about Jerry Garcia in “Culture & Art.” You can also find the digitized research archives of Albert Hofmann, who first synthesized LSD. But the centerpiece of the site is “Plants & Drugs.” Each substance has a “vault,” which includes pages on such topics as dosage, effects, legal status, and history. Some of that information is derived from “experience reports,” which are descriptive accounts of drug trips that anyone can submit.

Since 2000, Erowid has received more than a hundred thousand reports and has published about a quarter of them. Some are positive: “The Inner Eternity,” “Spiritually Orgasmic.” Others are not: “Existential Horror,” “Unimaginable Depths of Terror,” “Convulsions, Seizures, Vomiting.” Reports are reviewed by a few dozen specially trained volunteers, who range from college students to computer scientists. Each submission is read twice, and the best ones are passed on to a handful of senior reviewers for final selection.

At one time, the samizdat on drugs was so rare that those who found it seemed like sages at parties and in college dorms. Earth and Fire call such enthusiasts, and anyone extremely knowledgeable on the subject, drug geeks. Earth said that he “considers it an honor” to be among them. In the eighties, President Ronald Reagan’s war on drugs sent the geeks into hiding. An ad sponsored by the Partnership for a Drug-Free America featured a father delivering a tearful graveside monologue, and showings of some Hollywood films included public-service announcements from the likes of Clint Eastwood and Pee-wee Herman, who held up vials of crack before the phrase “The thrill can kill” appeared on the screen. People who wanted both to try drugs and to know the risks had difficulty finding any credible guidance.

But by the mid-nineties a fragmentary drug-geek community had started sharing information on e-mail lists such as Leri, Web sites such as Deoxyribonucleic Hyperdimension, and Usenet groups such as alt.drugs.psychedelics. The geeks and the government continued to ignore one another. In 2002, during a talk at the consciousness-studies conference Mind States, in Jamaica, Fire said, “From the establishment viewpoint, it’s surprising if new data come out of the drug-using community. In the drug-using community, it’s surprising if information that’s useful comes out of the establishment.” Earth and Fire’s idea was to close the rift: to maintain a comprehensive data set that could serve as a primary reference for everyone from the village stoner to the national drug czar.

Edward W. Boyer, the chief of medical toxicology in the department of emergency medicine at the University of Massachusetts Medical School, in Worcester, first became aware of the drug-geek sites in 1997. A pair of high-school students had ended up in his emergency room after going online and learning how to synthesize the sedative GHB at home. “My first thought was, It’s really bad—people are potentially learning online about new drugs to abuse,” he said.

In 2001, Boyer wrote a research letter to the New England Journal of Medicine alleging that Erowid and other “partisan” Web sites were outperforming federal antidrug sites in the search results for ecstasy, GHB, and certain other drugs. But during the aughts Boyer paid attention to assessments of new drugs as they went up on Erowid, and found that his emergency department did not receive an influx of poisonings. Instead, Erowid taught Boyer the street names of unfamiliar drugs, along with the basic chemicals that they contained. “We emergency physicians pride ourselves on being pretty close to the street,” Boyer told me. “Erowid just blew the doors off what we do.”

According to the 2014 National Survey of Drug Use and Health, nearly half of Americans over twelve have tried an illicit drug. They may borrow Adderall from a friend to work harder, or Xanax to reduce anxiety; they may use cocaine to have more fun at a party or ayahuasca to contemplate the great questions of life. Today’s experimenters can also partake of many new psychoactive substances. In recent years, suppliers have expanded into a wide range of synthetic chemicals that, until they attract government attention, go untargeted by molecular bans in the United States and abroad. Once they have been prohibited, these “research chemicals,” as Earth and Fire call them, can be modified in labs and sold anew; they are often cheap and can be bought through online marketplaces.

Erowid is an educational nonprofit, whose mission is to “provide and facilitate access to objective, accurate, and non-judgmental information” about psychoactive substances. Users can assess benefits and risks by reading experience reports, and many vaults have a summary “Health” page. Erowid has also formulated a set of standard warnings, or “Erowid Notes,” which are used to flag risky activities in experience reports (“Driving while intoxicated, tripping, or extremely sleep deprived is dangerous and irresponsible because it endangers other people. Don’t do it!”).