A sprawling, endlessly complicated pro-Trump conspiracy theory has jumped from fringe social media sites to mainstream attention.

The signs, shirts and banners at a rally in support of President Trump on Tuesday were, to the uninitiated, baffling.

"We are Q," read one sign at the event in Florida.

"WHERE WE GO ONE WE GO ALL," read another.

Others wore T-shirts with the letter "Q" and slogans such as "The Great Awakening".

All are references to a conspiracy theory gripping fringe pro-Trump activists - albeit a growing number of them, including celebrities, media personalities and influential social media accounts.

It's nebulous and continuously changing to adapt to current events, but the overarching conspiracy theory has been given a name: "QAnon".

Image copyright EPA Image caption As President Trump speaks at a rally in Florida on 31 July, a QAnon poster is visible (bottom right)

Image copyright EPA Image caption One of dozens of QAnon-themed signs and T-shirts captured by cameras during the rally

What is it?

The story began in October 2017, when an anonymous user posted a series of messages on 4chan - a very loosely moderated message board which has been a breeding ground of a number of online movements, including the alt-right.

The unidentified user, who signed off as "Q", claimed to have top security clearance within the US government.

The baseless core of the QAnon story is that the Mueller investigation into alleged collusion between the Trump campaign and Russia is actually an investigation into global elites, and that the president is masterminding a secret plan to arrest top politicians and Hollywood stars for corruption and child abuse.

For some reason, this plan is being revealed to niche internet message boards, via Q, through cryptic messages that frequently do not appear to make any sense (or are open to countless interpretations). For example:

"Do you believe in coincidences?

"'Blunt & Direct Time'

"BDT.

"Think currency.

"Think fireworks."

Despite the farfetched, open-ended and inscrutable nature of Q's messages, they quickly gained a cult following. Other users began to interpret the clues - or "breadcrumbs" - and elaborated on the theory.

The resulting QAnon conspiracy theory - also known as "The Storm" - is a collection of these interpretations. The "Anon" part of the name comes from the fact that 4chan posters are, by default, anonymous.

It echoes the debunked "pizzagate" saga - which resulted in a man opening fire in a Washington pizza restaurant in 2016. He believed a Democratic Party-run paedophile ring was based there.

Despite there being no real evidence that Q has any special insight into the inner workings of the government, the conspiracy theory has been pushed by various celebrities in the US.

The actress Roseanne Barr, former baseball player and current Breitbart podcast host Curt Schilling, and Infowars host Alex Jones - who has spread other conspiracy theories, including one which claimed that a massacre at a Connecticut school was staged by the government - have all promoted the theory.

Image copyright Twitter

It's not always clear whether the people pushing the conspiracy theory really believe that the contents of Q's cryptic messages are meaningful, or whether they are using it to provoke political opponents and the media.

Many alt-right and far-right social media figures have been known to ironically latch onto conspiracy theories - including "pizzagate" and others - to bash liberals and mainstream conservatives, or mock legitimate news outlets.

But it's also clear that QAnon has hooked some true believers.

A man recently blocked a bridge near the Hoover Dam in Arizona using a homemade armoured truck, and held up a QAnon-related sign to the window. Since being arrested on terrorism charges, he has written letters to President Trump peppered with various QAnon slogans.

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The cryptic messages from Q have now migrated over to 8chan - another anonymous forum with extremely light moderation rules - but the theory has also filtered into more mainstream platforms including Twitter, Facebook, YouTube and Reddit.

Image copyright Getty Images Image caption The conspiracy has spread to mainstream social networks such as Reddit

And according to NBC, the QAnon conspiracy app "QDrops" made the top seller list in Apple's App Store and Google's Play Store when it launched in April.

Will Sommer, a journalist at the Daily Beast who writes a newsletter about right-wing media, says QAnon supporters tend to be older people who are "a little less sceptical about what they see on the Internet".

He covered a small QAnon rally in Washington, which was made up mostly of middle-aged Americans, some of whom had travelled from hundreds or thousands of miles away. It wasn't a crowd, he says, that you would normally associate with niche message boards.

"It's really taking off, at least within the American right, and amongst Trump supporters," says Sommer.

The timing of the conspiracy theory's origins, he says, is no accident. During the Mueller investigation, "people were really looking for reasons to not think that the president is somehow in the employ of Russia, or that something nefarious had happened during the campaign."

Trump and conspiracies

Q acolytes pay close attention to President Trump's speeches, and although he has never directly referenced the theory, the president has promoted conspiracy theories to his supporters in the past - most notably the false idea that former President Obama was not born in the United States.

Joseph Uscinski, associate professor at the University of Miami, says Trump built his support amongst "more conspiratorially inclined Republicans".

During the 2016 election campaign, Trump suggested that Rafael Cruz, the father of his main opponent Ted Cruz, was connected to the man who killed President John F Kennedy. Although there was no evidence for the claim, Uscinski says that Trump "had to keep going with these conspiracy theories to keep his prime constituency motivated."

Media coverage

The incident in Arizona, the tweets by Rosanne, and the prominence of Q signs at Tuesday's rally in Tampa has led to more coverage of QAnon in the media.

Whitney Phillips, assistant professor of communication, culture and digital technologies at Syracuse University, says that media outlets need to be careful they are not drawing more people into conspiracy theories.

She says "if a particular conspiracy only exists within a particular community, all reporting will do is amplify that concept so that more and more people are exposed to it."

Phillips acknowledges that "at this point, not reporting on the story (of QAnon) could be framed as being irresponsible, because it is happening and people are responding". However, she argues that conspiracy theories "don't occur in a vacuum" and warns that even articles debunking theories can legitimise their ideas.

"Not only do these individuals tend to follow mainstream media coverage very closely, they tend to cater their messages to maximize media exposure," she says. "They love it when they're in the news."

Certainly Q - whoever it is behind the messages - is lapping up the attention. In recent days Q has posted links to media stories and has claimed the coverage is "right on schedule". On Thursday the account published a new message:

"Welcome to the mainstream.

"We knew this day would come."

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