An electrolytic capacitor uses an electrolyte (a liquid of gel containing a high concentration of ions) to achieve a large capacitance than the other capacitor types. These electrolytic capactiors are polarized, meaning that the voltage on the positive terminal must always be greater than the voltage on the negative terminal. They are commonly used as filters in devices in various power supples to reduce the voltage ripple as well as input and output smoothing as an LPF.