Capacitors are the essential energy reservoirs of electronic circuits. They specialize in storing and releasing electrical charge, performing critical functions such as power supply filtering for stable voltage and signal coupling/decoupling. In reference to the dielectric material incorporated within, capacitors have different types—ceramic, aluminum electrolytic, film, and tantalum—each with distinct trade-offs in size, cost, parametric stability, and frequency response. Understanding these differences is crucial for selecting the optimal capacitor, whether the priority is miniaturization, high capacitance, ultra-low ESR, or high-voltage handling for applications ranging from consumer devices to industrial systems.