A capacitor is an electronic component used to store and release electrical energy. It consists of two conductive plates separated by an insulating material called a dielectric. When a voltage is applied, the plates accumulate charge, and the capacitor stores this energy. Capacitors are used in various electronic circuits for functions such as filtering, energy storage, signal smoothing, and timing. They come in different sizes and types, such as electrolytic, ceramic, and tantalum capacitors, each suited for specific applications.