Page "Guitar" Paragraph 103

On guitars that have them, these components and the wires that connect them allow the player to control some aspects of the sound like volume or tone.

These at their simplest consist of passive components such as potentiometers and capacitors, but may also include specialized integrated circuits or other active components requiring batteries for power, for preamplification and signal processing, or even for assistance in tuning.

In many cases the electronics have some sort of shielding to prevent pickup of external interference and noise.