The skin effect occurs in conductors of alternating current (AC). The term describes the tendency for an electric current to become distributed within a conductor closer to the surface of the conductor than to the core. As frequency increases, the current density becomes more concentrated along the "skin" of the conductor. The skin effect is caused by opposing eddy currents, and increases effective current resistance within the wire. The effect can be mitigated by using litz wire, which is comprised of wires small enough to counteract the skin effect that takes place in larger high-frequency wires.