Pull down resistor

A Resistor (typically 1k-100k Ohms) used to gently lower the voltage to ground of a line if nothing else is driving it up. Resistance is usually set to a value that prevents excessive (for a typical microcontroller application, usually >1mA) current from flowing.

Typically used on active-high inputs to prevent transient voltages from accidentally making the line appear high such as engaging a mosfet due to noise. Also see pull up resistor.