Potentiometers, or "pots" for short, are means of adding variable resistance control to your circuit. Each potentiometer is rated from 0 to the marked amount of Ohms on the potentiometer. In this instuctable, I am using a 1000 Ohm, or 1 Kilo Ohm, potentiometer. I demonstrated this property of the potentiometer by using a digital multimeter set to the Ohm symbol.
Potentiometers have three leads. By connecting a circuit to the outer two leads, the resistance of the potentiometer will match the resistance marked on the potentiometer. It will behave like a normal resistor. When the circuit is connected to a center lead, and an outside lead, the potentiometer will behave like a variable resistor - turning the post of the potentiometer will increase (clockwise), or decrease (counter-clockwise) the resistance of the potentiometer.