A potentiometer is a type of variable resistor. These passive components are designed to control electrical resistance, measured in Ohms (Ω). Multiple different variations are available, including trimmer and rotary potentiometers, but the functional principle remains the same.
Potentiometers work by picking up an input Voltage and transferring different amounts to a circuit. This amount is determined by the position of the wiper (sometimes also known as a slide) on a resistive track. This explanation briefly describes how potentiometers can be used as voltage regulators, but they can also be used to introduce different levels of resistance, to compare the electromotive force (EMF) of two cells, or to regulate the power in a circuit. In the latter case, it is a rheostat.
A typical example of a potentiometer application is the volume control on radio and stereo systems. Some still have analogue rotary potentiometers installed and despite increasing digitalisation, potentiometers are often used in electronics like these.
Potentiometers may also be referred to as pots or potmeters.