A type of capacitor created using two aluminum foils, one of which is coated with oxide, that are separated by paper soaked in an electrolyte — a conductive liquid. The oxide-coated foil serves as the anode, while the paper/uncoated foil serve as the cathode. Leads (wires) are attached and the foils are rolled up and placed inside an aluminum casing. Because they can provide the highest capacitance of any type of capacitor, electrolytics are often used for power supply filters. Electrolytics are polarized, meaning they have anodes and cathodes, and must be oriented in a circuit properly. Electrolytic capacitors tend to have a shorter lifespan than some other types, and generally have wider tolerances and smaller effective temperature ranges.