Transistor

In electronics, a transistor is a semiconductor device that allows a signal at its input terminal(s) (usually a current or a voltage) to control an output signal at its output terminal(s), acting either as a switch activated by the input signal or as an amplifier for the input signal. The most common transistors are the three-terminal bipolar transistor and the four-terminal Metal-oxide-semiconductor field-effect transistor or MOSFET.