Humans are pattern seekers. It’s how we’ve always made sense of the world: Our ancestors wouldn’t have survived if they hadn’t realized that plants tend to flourish after rainfall or that sabertooth tigers tended to eat them. But sometimes we’re just a little too good at finding meaning in the noise, occasionally unable to separate real patterns from those of our own imagining. These days, your pattern matching skills will help you find Waldo, but they are also why celebrities’ faces keep popping up on tortillas. At their most paranoid and byzantine, these pattern-matching misfires are called conspiracy theories: unfounded, deeply held alternative explanations for how things are—often invoking some shadowy, malevolent force masterminding the coverup.

Conspiracy theories thrive on the internet, but that’s certainly not where they were born. The Flat Earth Society has existed since the 1800s, and people have been speculating about which people are secretly living or dead at least since 68 AD, when Romans weren’t convinced their arsonist emperor Nero had actually committed suicide. But conspiracies and the digital world do mesh well, probably because they scratch similar itches in our not-quite-domesticated psyches. Internet culture runs on people sinking huge amounts of effort into obscure and seemingly pointless undertakings. And conspiracy theories are to people what an unsupervised toddler is to a bored border collie: It may not look quite like a sheep, but when you nip at its ankles, your brain sure feels like it’s doing its job. The combination of the endless internet and your pattern-hungry brain has managed to spread webs of red string farther than was ever before possible.

On the web, it’s often hard to distinguish real conspiracy theories from gleefully ironic acts of collective world building—and either way, speculating about which celebs are immortal vampires and which are secretly lizards is mostly harmless fun (and excellent meme fodder). But because many dark and usually racist pre-internet conspiracies have found new homes on the web, you’re always a digital hop and a skip from the mind-bending alternate universes controlled by many of the same people responsible for our fake news crisis.

Online Conspiracy Theories The WIRED Guide

The History of Online Conspiracy Theories

The kind of conspiracy theories that wreak havoc on the internet have knowable ancestors: the conspiracies that erupt every time there’s a significant advance in communication technology. Take mass printing. The Protocols of the Elders of Zion is a fictitious pamphlet cooked up in 1903 to spread the idea that a ghoulish Jewish cabal was bent on overthrowing the virtuous (Christian, white) nation state. Thanks to the high-speed rotary printing press, the conspiracists were able to slip it into libraries across Europe, and because people trusted their libraries, it was believed. The result: populations turning a blind eye to Russia’s Jewish pogroms, and, later, to Nazi concentration camps. Around the same time, the (also anti-Semitic) Dreyfus affair used newly cheap and reproducible lithographs to spread anti-Jewish imagery.

Then came the radio. People heard ghosts in its crackles and echoes. Enigmatic “number stations” have fascinated conspiracy theorists since World War I. (There’s a station called the Buzzer that’s been broadcasting a continuous pulse since the 1970s—conspiracy fans think it might be part of an automated Soviet doomsday project, and that the world will end when it goes off the air.) Television was subjected to the same kind of scrutiny and symbol hunting: In the 1940s, some thought Tom and Jerry was Nazi propaganda; footage of the moon landing has been checked and rechecked for evidence of fakery for decades.

With new technology comes new gaps in the public’s understanding of their world, and, for conspiracy theorists, new ways to manipulate those gaps. So the thing that makes the internet wonderful—that it is a near-endless, low-cost repository of information accessible by billions—is also what makes its so fertile for conspiracy. Early internet users were a generation trained on in-person and over-the-phone communication. Digital slang was in its infancy, the emoji that give context to chats didn’t exist, and users were faced with more information than they’d ever been exposed to before. Not only did you often confuse your peers with your ambiguous late-night typing, it was easy to wade into the web and emerge confused and overstimulated yourself.

Which brought forth communities united by laser-focused citizen sleuthing. In 1996, a spate of anonymous word-salad gibberish posts, all entitled Markovian Parallax Denigrate, flooded Usenet groups. Internet sleuths noticed that one of these messages seemed to come from controversial (and conspiracy-minded) antiwar activist Susan Lindauer, who claimed to be a CIA asset and to have reliable intel that 9/11 was an inside job. The conspiracy engines started turning and suddenly phrases like “refrigerate morphine napkin inland Janeiro nameable yearbook hark” were seen as the CIA’s digital-age take on the number station. At the same time, usenets devoted to Whitewater (a corruption probe focusing on Clinton real estate investments) sprang up and connected dots like Bill Clinton’s alleged cocaine habit, handwriting samples, and plane crashes to claim that White House deputy counsel Vince Foster’s suicide was actually a murder.

When video and easily manipulable images became more common, the landscape got loopier. Admit it, you were fooled by a Photoshopped image or two back in the day. (Remember Helicopter Shark?) But you don’t need to start ’shopping to fall down a photographic rabbit hole. Love (or hate) a celebrity? With a few keystrokes, you can comb through just about every paparazzi photo ever taken of them and watch videos of their interviews and public appearances for hours on end until you’re positive there’s some funny business going on. An alleged aversion to pens and emoji-heavy Instagram captions convinced some that Glee star Lea Michele can’t read. A monomaniacal focus on Katy Perry’s eye and eyebrow shape has led some YouTubers to believe the singer is actually murdered child-pageant star JonBenét Ramsey all grown up.

As internet access expanded, the massive scale of web conversation contributed to some weird delusions. Large groups innocently chatting about their childhoods have spawned some of the most enduring internet conspiracy theories. So many people are positive that they saw a nonexistent movie called Shazaam, in which comedian Sinbad supposedly played a genie. He has repeatedly denied ever starring in such a film. This collective misremembering is called the Mandela Effect because apparently heaps of people also remember Nelson Mandela dying in prison. (It’s also responsible for frequently misquoted movie lines like “Play it again, Sam” and “Luke, I am your father.”)

The same forces are at work on today’s internet, too. We may have GIFs and emoji to bring affect to our text-based messages, but, partly due to the internet’s irony-soaked culture, it’s still almost impossible to tell who is being serious. (This phenomenon is so prevalent that it’s entered the internet rule book and is now known as Poe’s Law, after a poster named Nathan Poe who was baffled by creationists and those parodizing them.) Poe’s Law is how jokes and memes jump the fence to become full-blown conspiracy theories on today’s internet. A decade ago, a satirical post citing some seemingly missing arm freckles and angsty lyrics, pronounced Avril Lavigne—like so many celebs before her—dead, and replaced by a dopplegänger named Melissa. In 2016, a quip about US senator Ted Cruz being the Zodiac Killer has blossomed into a mythology of its own, even though he was an infant during most of the killings. (Clues: Cruz sort of/not really looks like an old police sketch and has a slightly unsettling—perhaps serial-killer-esque, apparently—obsession with having a pantry well-stocked with cans of soup.)

Citizen sleuths—or, as some call themselves these days, citizen journalists—have only become more prevalent as access to information continues to increase. And sometimes these conspiracies do turn out to be true, like the Pixar connected universe theory, which links together dozens of Easter eggs, like recurring brand names, and split-second cameos to conclude that all Pixar films take place in the same world. Disney finally confirmed the theory in 2017.

At the most bizarre and all-encompassing, you get the internet edition of the now centuries-old obsession with the Illuminati: a secret cabal of (sometimes alien, sometimes reptilian, sometimes alien-reptile) elites who control the world to suit their own ends by meeting in underground bunkers and operating a celebrity-murder and -cloning station headed by Queen Elizabeth II. Almost every major celebrity has been accused of being a member. Some have dealt with it skillfully by ignoring it. Others, like Facebook’s Mark Zuckerberg, who some believe to be an extraterrestrial lizard person because of his round eyes and awkward mannerisms, have played directly into conspiracy theorists hands by saying things like “I am not a lizard.” Which, of course, is what a lizard would say.

Q Who? Tracing the rise of the baroque criminal-political conspiracy theory known as QAnon.

October 5, 2017: President Trump makes an ambiguous comment about a military dinner being “the calm before the storm,” sparking conspiracist speculation.

October 28, 2017: An anonymous user who later claimed to be a high-level government informant writes a cryptic post bursting with far-right conspiracy bait about Hillary Clinton, Huma Abedin, and George Soros on 4chan’s infamous /pol/ board. The user is nicknamed Q, after the Department of Energy’s top-secret security-clearance level.