Video narration
When you plug an appliance into a wall outlet, do you picture electricity flowing steadily in one direction? That's not quite what happens. In the outlet, the current moves back and forth, repeatedly reversing direction. That motion is AC, or alternating current. In many systems, a complete back-and-forth cycle happens 50 or 60 times per second. DC is different: it flows primarily in one direction. So AC at your wall outlet is this repeated reversal powering your appliance.