A changing electric current produces a magnetic field, and a changing magnetic field induces an electromotive force, and the coefficient of the linear relationship between the two is called inductance.

An ideal inductor does not produce or consume any energy, while the inter-conversion of electricity and magnetism can serve to store or release energy.
According to Ohm's Law, we can observe the following phenomena in an inductor: 1) The induced current cannot change instantaneously; 2) the phase will lag the voltage by 90 degrees; and 3) if the current doesn't change, no electromotive force will be induced.

This is why inductors are used to stabilize current, and can be used for phase matching or as low pass components. Of course inductors have an even wider range of applications, including storing energy, releasing energy, resonating, and acting as bypasses.

While the discussion above refers only to an ideal inductor, such has yet to be manufactured in the real world. The characteristic of any passive component, be it a resistor, capacitor, or inductor, is simply its optimum performance in an equivalent circuit, within a certain frequency range.