Metal prongs on a type-A electrical plug. - JACKREZNOR/Shutterstock Most gadgets and small appliances in U.S. homes have either a Type A or Type B electrical plug, perhaps with a cover to hide cords.

Plugs where one blade is wider than the other can be annoying, but they'll also keep you a lot safer. Here's why they're like that and how it works.

You find yourself in an airport or hotel room in another country, and you really need to charge your phone, camera or game system. But what is that strange-looking outlet? It has round holes! And ...