Passive electronic components that store and discharge electrical energy, essential for power circuits, control circuits, and noise filter circuits in manufacturing equipment. Various types include aluminum electrolytic capacitors, tantalum capacitors, ceramic capacitors, and film capacitors, used in servo control circuits of NC machine tools, smoothing circuits of inverter devices, power supply sections of PLCs, and noise suppression circuits of measuring instruments. Selection is based on capacitance value, withstand voltage, temperature characteristics, and ESR characteristics, with high reliability and long-life products required for industrial applications. Unlike resistors and inductors, they have characteristics of passing AC signals and blocking DC signals.