What is the basic function of a capacitor?

A capacitor stores electrical energy in an electric field between two conductive plates separated by an insulator (dielectric). It can charge up and then release that energy, which makes capacitors useful for smoothing out voltage, filtering signals, and providing short bursts of power. Capacitance is measured in farads. Unlike a battery, a capacitor stores energy electrostatically and can charge and discharge very quickly. Knowing that a capacitor stores charge — distinct from a resistor (limits current) or inductor (stores energy in a magnetic field) — is standard component knowledge.