A rheostat is a type of variable resistor. Use it to control the amount of electric current in a circuit.

It works using a sliding contact, called a wiper, which moves over a resistive material. When you move the wiper, the resistance changes. As a result, the current in the circuit increases or decreases.

In simple words, a rheostat lets you adjust how much electricity flows, just like a dimmer switch controls the brightness of a light.