Inductance is the property of an electrical conductor that opposes a change in the electric current flowing through it. It is defined as the ratio of the induced voltage to the rate of change of current causing it. Inductance is a proportionality constant that depends on the geometry of circuit conductors, such as cross-sectional area and length, and the magnetic permeability of the conductor and nearby materials. The unit of inductance in the SI system is the henry (H), named after Joseph Henry, which is the amount of inductance that generates a voltage of one volt when the current is changing at a rate of one ampere per second.

An inductor is an electronic component designed to add inductance to a circuit. It typically consists of a coil or helix of wire, and a coiled wire has a higher inductance than a straight wire of the same length. Inductance is used in many areas of electrical and electronic systems and circuits, and electronic components that add inductance to a circuit can be in a variety of forms and may be called by a variety of names, such as coils, inductors, chokes, and transformers.

Inductance is classified into two types: self-inductance and mutual inductance. Self-inductance is the property of a circuit, often a coil, whereby a change in current causes a change in voltage in that circuit due to the magnetic effect caused by the current flow. Mutual inductance is an inductive effect where a change in current in one circuit causes a change in voltage across a second circuit as a result of a magnetic field that links both circuits.

In summary, inductance is a fundamental parameter in electrical and electronic circuit designs that affects all circuits to some degree. It is the ability of an inductor to store energy in the magnetic field that is created by the flow of electrical current, and it is used in many areas of electrical and electronic systems and circuits.