A farad is a unit of measurement used in electronics. It is used for capacitance, which is the ability to store electric charge. The unit is named after the English physicist Michael Faraday. The different sizes of farad are: farads (F), millifarads (mF), microfarads (μF), nanofarads (nF) or picofarads (pF). The farad is a large unit of capacitance. Typical devices have capacitances ranging from microfarads to picofarads.