Video narration
Why would electricity be allowed through a component in one direction, but stopped when you turn it around? Think of a diode as a one-way door for electric current. When you connect it the right way, the door opens, and current passes through. Turn the battery around, and here is the surprising part: it does not make current travel backward through the diode. It mostly closes the door instead. So, in the forward direction, current passes; in reverse, it is mostly blocked. "Mostly" matters, because a real diode is not a perfect door. A little leakage can still occur, and it may need a small push before conducting. You do not need equations to use the idea. A diode lets current flow mainly one way, like a one-way door, so a circuit can control where electricity goes in everyday circuits.