Capacitance

It is the ability of a device to store charge for a given applied potential difference.

A capacitor is a device that stores charge.

$C=Q/V$

For a parallel plate capacitor of plate area $A$, spaced apart at a distance $d$,

$C=\frac{ϵA}{d}$, or

$C=\frac{k{ϵ}_{0}A}{d}$, where $k$ is the dielectric constant, or relative permittivity.