Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a magnetic field.

Eddy current techniques are commonly used for the nondestructive examination (NDE) and condition monitoring of a large variety of metallic structures, including heat exchanger tubes, aircraft fuselage, and aircraft structural components.  In aerospace production, every aircraft structure component will undergo inspection by one of the primary NDT methods. In-service aircraft will experience subsequent nondestructive testing, eddy current inspection being one the primary methods.