Capacitance, also known as "capacitance," refers to the quantity of free charge stored under a given potential difference, denoted as C, with the international unit being the farad (F). Generally, charges move under the influence of an electric field. However, when a medium is introduced between conductors, it hinders charge movement, causing charges to accumulate on the conductors. This accumulation of stored charge is called capacitance.

Capacitance refers to the ability to hold an electric charge. Any electrostatic field is composed of numerous capacitors, and where there is an electrostatic field, there is capacitance, which is described by the electrostatic field. It is generally believed that an isolated conductor with an infinite distance constitutes a capacitor, and grounding a conductor is equivalent to connecting it to an infinite distance, forming an integral connection with the earth.

Capacitance, or sometimes referred to as capacity, is a physical quantity that represents a capacitor's ability to hold electric charge. In physics, capacitance is a static charge storage medium, where electric charge may exist, which is its characteristic. Its applications are extensive; it is an indispensable electronic component in the fields of electronics and electricity. It is mainly used in circuits for power filtering, signal filtering, signal coupling, resonance, compensation, charging and discharging, energy storage, and blocking direct current.