Capacitance is a property of electric circuits that describes how much electricity is stored between two plates or wires. It is defined as C=Q/V, where C stands for capacitance, Q for charge, and V for voltage.
The farad, named for Michael Faraday, is the unit of capacitance in the SI system. By rolling up the plates into a single cylindrical component, the volume of a capacitor can be greatly reduced. It is now possible to buy capacitors as powerful as one or two farads, and super-small capacitors in the kilofarad (one thousand farads) range are being developed in Britain.