An electrolytic capacitor is a type of polarized capacitor that uses a wet electrolytic solution and an oxide film to store electrical charge. An example is the aluminum electrolytic capacitor which contains two closely spaced spooled strips of aluminum foil for the positive anode and negative cathode. These are separated by a thin spacer material soaked in the wet electrolyte. The thin insulating layer of aluminum oxide formed on the anode between the foil plates acts as the dielectric, creating a high-capacitance device in a compact package. These polarized capacitors are well-suited for applications where space and weight are at a premium, such as in electronic devices, power supplies, and filtering circuits.