capacitor

A capacitor is a tiny energy reservoir built from two metal plates sitting close together but not touching. When you connect it to a voltage, charge piles up on the plates — negative on one side, positive on the other — and the gap between them holds an invisible electric field. Think of it like a small water tank: you can fill it up quickly, hold the water for a moment, then let it gush back out when you need it.

Because charge can flow in and out, a capacitor smooths out bumps — when power dips for an instant, it releases stored charge to fill the gap, which is why nearly every device has them steadying its supply. It also blocks steady DC (once full, no more flows) but readily passes changing AC, since the plates keep filling and emptying. Pair it with a resistor and you can set precise timing, like the slow blink of a turn signal.