One day last year, at the height of the Ukrainian revolution, Mark Howard spotted something interesting on television. In the background, a protester was holding up a poster with an instantly recognizable logo: A “B” with two vertical bars, the symbol for the digital currency bitcoin.

Mr. Howard is an American IT specialist and a self-described bitcoin enthusiast. He surmised that the poster’s QR code, which is a kind of square bar code, must contain the address of a bitcoin wallet belonging to the protesters. On a whim, he froze the frame, scanned the code with an app on his phone, and sent $10 worth of bitcoin to a country whose banks were paralyzed but whose protesters needed money to continue their fight.

It happened instantly, and the total cost of the transaction was $0.02.

If using unregulated cryptocurrency to crowd-fund foreign revolutions sounds like a quintessentially 21st-century edge case, here’s a thing you need to know: The same fundamental technologies that enabled Mr. Howard’s impromptu act of foreign aid are being used by hundreds of other companies, in many countries, to do something that has never happened in the history of money: Exchange it at any distance, nearly instantaneously and for near-zero transaction fees.

We are just at the start of understanding what this will mean. The safe bet is that the easier it is to exchange money, the more of it will be exchanged, with obvious implications for economies that successfully integrate these technologies.