Define dielectric and capacitance as used in electrostatic?

Dielectric: A dielectric is a material that does not conduct electricity, but can become polarized when placed in an electric field. This polarization creates an electric dipole moment within the material, which can store energy in the form of electric potential.

Capacitance: Capacitance is a measure of a capacitor's ability to store electric charge. It is defined as the ratio of the electric charge stored on one of the capacitor's plates to the potential difference between the plates. The unit of capacitance is the farad (F).