here was a time when people happily used chickens, pigs, or a nice pile of lumber as payment for a cow, some clothes, or anything else of value. And then some smart people got behind a breakthrough—they introduced currency.

Swatches of buckskin, stamped pieces of gold, and later, paper notes—these were a mighty intellectual and technological leap ahead from that clucking bird. It may not seem like it in today's world, where cash has a whiff of the downright prehistoric, but paper currency was mind-blowing in its heyday—the first U.S. government-issued currency debuted during the Civil War—because of its advanced features: It was lightweight, portable, reliable (hyper-inflationary events notwithstanding), efficient, and powerful. These are descriptors we might apply to the latest smartphone today.

The point is, currency for hundreds of years has been an evolving form of technology, with the faster, better, cheaper underpinnings found in all great technologies. But arguably, not since the arrival of the greenback has currency been poised for a more dramatic leap forward. Digital currency is finally taking hold.