In the cold calculus of presidential politics, here's how things are supposed to work. You spend hours of travel time going from campaign rally to campaign rally, where if you're lucky and your staff has found a big enough venue, a few thousand people will watch you give the same old stump speech. You hope it'll get picked up in the news, even though the last thing you'll be doing is breaking news (unless it's for an unplanned gaffe).

If you answer questions, it's in a controlled Town Hall format, not a cacophonous free-for-all. You trumpet your appearances in advance for maximum exposure. And you certainly don't try for anything major during your opponents' convention.

President Obama broke all those rules Wednesday afternoon, when he became the first candidate of either party to do an AMA ("ask me anything") on Reddit. The appearance was a complete surprise, even for veteran Redditors (who immediately demanded Obama post a picture to prove it was him; he complied).

The president also broke news, floating the idea of a constitutional amendment to overturn the Supreme Court's Citizens United decision (which gave rise to Super PACs) for the first time.

The Value of a Connected Audience

Though the AMA was unannounced, word quickly spread on Twitter, and Reddit's servers were overwhelmed. The site said more than 200,000 people were trying to view Obama's Q&A at any one time. More than 1.8 million people subscribed to the thread.

Ask any politician if they would like to speak directly to 1.8 million people for an hour — or even 200,000 — and they'll probably start weeping with joy at the thought. For comparison, Obama's DNC acceptance speech in 2008 — held in the open air at Mile-high stadium in Denver — had a capacity crowd of 84,000.

So let's recap. Obama sat at a laptop for one hour, typed out answers to all of ten questions (leaving hundreds unanswered), ending with a quick in-joke referencing a popular meme (the "not bad" Obama rage face). In return he won the attention and interest of nearly 2 million people on Reddit, and many more without. (On the Internet, Reddit has a coolness factor that goes far beyond its borders.)

Creating New Rules

Regardless of your affiliation, that kind of return on investment has to change the political calculation. Don't be surprised, in 2016, if candidates from both parties spend a lot of time doing online AMAs — official ones on Reddit, and otherwise.

Is that a good thing? There are reasons to think not. The AMA format does allow candidates to cherry-pick which questions they're going to respond to. It's "ask me anything," not "I'll answer everything."

Then again, it would be hard for politicians to ignore questions that get a lot of upvotes, making the format superior to, say, a Twitter Town Hall. And giving the candidate time to type out answers is something of a win-win: the candidates gets to double-check their answer for gaffes (though Obama did accidentally refer to "a asteroid" in response to a NASA question), while the questioner gets a more measured, longer response.

To paraphrase Winston Churchill, the AMA may be the worst form of political Q&A — except for all the others that have been tried.

BONUS: Obama Reddit Photo Gets Meme Treatment