The nation's power grid pulses with a certain type of electricity: AC power. But our "Planet Money" team explains why some people are trying to revive the DC power grid. We don't think very much about ...

It is the bane of worldwide travel: there isn’t just one way to get AC power from the wall. The exact connector — and what you can expect when you plug in — differs from country to country. Even if ...

Ok, maybe not every country, but with at least 12 different sockets in widespread use it sure as hell feels like it to anyone who’s ever traveled. So why in the world, literally, are there so many?