Aluminum electrolytic capacitors use aluminum as the anode, a liquid electrolyte as the cathode, and aluminum oxide as the dielectric. Their characteristic feature is the formation of microstructures on the surface of aluminum foil through electrochemical processes to increase surface area and thereby achieve high capacitance. They are the most widely used type of capacitor. Products with ultra-low equivalent series resistance (ESR) using solid conductive polymers instead of electrolytes are also widely utilized. In recent years, hybrid capacitors combining electrolytes and conductive polymers have emerged. Aluminum electrolytic capacitors continue to evolve to provide optimal characteristics for various applications. They are used in household appliances (such as audio systems, televisions), power supplies, uninterruptible power systems (UPS), inverters, motherboards, monitors, communications equipment, computers and peripherals, optoelectronic products, and electronic stabilizers.