variable resistor is a resistor of which the electric resistance value can be adjusted.

inside Variable Resistors

Potentiometer
The potentiometer is the most common variable resistor. It functions as a resistive divider and is typically used to generate a voltage signal depending on the position of the potentiometer. This signal can be used for a very wide variety of applications including: amplifier gain control (audio volume), measurement of distance or angles, tuning of circuits, and much more

in EL-KIDS, potentiometer educated how to function resistant.