 Despite their enigmatic personalities, inductors may be the simplest passive electronic component. Just coil a length of wire and you've crafted an air core inductor, as opposed to an iron or ferrite core inductor. A simple wire conductor formed into a coil can store energy from electrical signals in its own electromagnetic field. This property, better known as inductance, is measured in units of Henry's, or micro Henry's, in this case. If the signal's frequency increases, it faces even more impedance across the inductor. This strong aversion to change means the inductor can be used as a low-pass filter, which is why you'll often find inductors in DC circuits filtering out high-frequency noise and keeping signals smooth.