Capacitors are passive two-terminal electrical components that store electrical energy in an electric field. They are commonly used in electrical circuits to reduce current flow, to increase voltage drop, to decrease voltage transfer, to produce electrical oscillations and for mechanical energy storage. A capacitor consists of two metallic plates separated by an insulating material called a dielectric, which can be air, paper, mica, ceramics, or plastic film. When a voltage is applied to the capacitor, the charges on the two plates are attracted to each other, creating an electrical field between them. The magnitude of the charge, or capacitance, determines the amount of energy stored in the capacitor. This energy is later released into the circuit when the voltage is removed.