(CNN) If you watched any of President Donald Trump's campaign rally in Tampa, Florida on Tuesday night, you likely caught a glimpse of people holding up signs with "Q" or "QAnon" printed on them. Those people are adherents of a broad-scale conspiracy theory that pits President Trump against a global elite seeking to murder him.

Yes, you read that right.

With QAnon moving from the fringes of Internet thought into something much closer to the mainstream, I reached out to the Daily Beast's Will Sommer , who has been writing and thinking smartly about QAnon since its inception. (Read his full explanation of QAnon here .) Our conversation, conducted via email and lightly edited for flow, is below.

Cillizza: Let's start simple: Where the heck did QAnon come from? And do we have any sense how many "members" it has or whether it is growing?

: QAnon started last October, when an anonymous person or group of people called Q started posting cryptic clues on 4Chan . Trump supporters eventually found these clues, which they call "breadcrumbs," and spun them into a whole counter-narrative that's contrary to just about everything that's actually happening in the world.

So, for example, Robert Mueller isn't investigating the Trump campaign -- QAnon believers think he's actually working with Trump to get Hillary Clinton.

It's hard to gauge the extent of QAnon believers, but I'd say that it's pretty wide-reaching among really hardcore Trump supporters. In April, QAnon believers marched in DC and they numbered something like 200 people, and it's only grown since then.

The other thing is that a lot of tenets of QAnon, especially the part about a "deep state" plot, aren't that different from what's on Fox [News Channel] or talk radio every day. So when a person already prone to support Trump hears about QAnon, they've been primed to believe this stuff by the rest of conservative media.

Cillizza: Is this just another garden-variety conspiracy along the lines of, say, Obama wasn't born in the US? Why has this become such a, well, thing?

Sommer: Unlike something like birtherism or : Unlike something like birtherism or Pizzagate , QAnon is a kind of mega-conspiracy theory that sucks in just about every conspiracy theory you can think of. Pizzagate is part of it, birtherism is part of it -- but so is the JFK assassination conspiracy theory, the idea that all these mass shootings have been deep-state false flags , and much more. The vague nature of the Q clues also means that you can sort of imprint whatever your personal issue is onto it.

The other strange thing about QAnon is that it's fundamentally a story being told by the side that's already in power. Normally, conspiracy theories, like the idea that George W. Bush stole the 2004 election or that Barack Obama was an illegitimate president because he was born in Kenya, are coming from a group that's trying to explain why they're out of power.

Instead, QAnon believers got the guy they wanted elected in the White House, but they didn't get everything they wanted or were promised. For example: they chanted "lock her up," but Hillary Clinton was never locked up. So they retreat to a fantasy world where Hillary Clinton will soon be sent to Guantanamo Bay.

Cillizza: "Q" him or herself seems to be a major source of interest. Is there ANY sense of who this person is? Whether it's a person or persons? Whether they have any ties to Trump?

Sommer: There are a lot of theories about who Q is. QAnon people believe in fanciful ideas like, maybe it's Trump or Dan Scavino or Michael Flynn. They're always on the hunt for clues or acknowledgments from the administration. For example, Trump said "17" a lot in his speech Tuesday night, which they took to be an acknowledgment of Q -- the 17th letter of the alphabet!

That's also why they've been bugging White House reporters to ask Sarah Sanders about Q. [Editor's note: White House press secretary Sanders was asked about QAnon in Wednesday's briefing: "The President condemns and denounces any group that would incite violence against any individual," she said.]

QAnon critics, on the other hand, tend to focus on various hucksters promoting QAnon. Lots of conspiracy theorists on the right have become alienated from QAnon after Q accused them of trying to profit from the movement, so it's become kind of a circling firing squad of people accusing each other of being Q.

I think Q is just some random person or group of people who started a troll that has gotten way out of hand. Or maybe, as with so many things these days, it's a Russian psy-op!

Cillizza: Why, suddenly, were there so many Q signs/supporters at the Trump rally last night? Coordinated effort? Coordinated how?

Sommer: There's actually been increasing Q believer activity all over this year -- billboards popping up, more attention from conservative celebrities [Editor's note: Like : There's actually been increasing Q believer activity all over this year -- billboards popping up, more attention from conservative celebrities [Editor's note: Like Roseanne and Curt Schilling ], people appearing at Trump rallies. I think the stuff last night was big for a couple reasons: 1) pictures of the ralliers in Q gear started circulating before the event and 2) because people with QAnon gear and signs were in advantageous positions to get in front of the cameras during the rally. So suddenly all these political and media people are watching Trump give his speech, and this QAnon sign with Seth Rich references gets in front of the camera.

Cillizza: Finish this sentence: "QAnon's impact on politics -- and Trumpworld -- is _________________." Now, explain.

Sommer: "QAnon's impact on politics -- and Trumpworld -- is dangerous."

I think what we've learned from the Pizzagate gunman is that people actually believe this stuff, and some percentage of these people are going to be willing to take action. The idea of global pedophile conspiracies, for example, is a huge part of QAnon, and that's exactly the kind of thing that appears to motivate people to commit these bizarre violent incidents.

In the broader perspective, I think it's just really bad for American politics to have a segment of the population becoming increasingly unmoored from reality. For example, a big tenet of QAnon is that the deep state tried to shoot down Air Force One with a missile. That's nuts! But if you're a QAnon believer, you think that actually happened.

I'd also say QAnon probably benefits Trump, because it helps the base ignore actual bad news about his administration. It also dramatizes the campaign to elect Republicans -- it's one thing if you're voting for the GOP or Trump because you want boring legislative stuff like lower capital gains taxes. But if you believe in QAnon, you think Trump and the Republicans are literally fighting a worldwide battle against a nefarious cabal. That makes politics more engaging.