A metal-oxide-semiconductor field-effect transistor (MOSFET) is a type of transistor used in modern electronic circuits. It is one of the most commonly used transistors, with over 5 billion shipped every year. The MOSFET is the most widely used transistor in both digital and analog circuits, due to its versatility and low cost. The MOSFET works by using an electric field to modulate the conductivity of a channel of n-type or p-type semiconductor material. The channel forms between the source and drain regions, and current flow is controlled by the voltage applied to the gate region. The gate voltage can either increase (turn the transistor "on") or decrease (turn the transistor "off") the channel conductivity, making the transistor either act as a switch or an amplifier.