MOSFET

The Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET, MOS-FET, or MOS FET) is a device used for amplifying or switching electronic signals. In MOSFETs, a voltage on the oxide-insulated gate electrode can induce a conducting channel between the two other contacts called source and drain. The channel can be of n-type or p-type (see article on semiconductor devices), and is accordingly called an nMOSFET or a pMOSFET (also commonly nMOS, pMOS). It is by far the most common transistor in both digital and analog circuits, though the bipolar junction transistor was at one time much more common.

=Reference=
 * http://en.wikipedia.org/wiki/MOSFET