A transistor is a semiconductor device used to amplify or switch electric power and signals.  It is one of the basic building blocks of electronic devices.  These usually have three terminals.  Their basic component is a semiconductor called germanium or silicone.
 A transistor can act as a switch or gate for electronic signals.  That is, transistors are used as electronic switches that turn electronic circuits on or off.


Transistors are divided into two categories as NPN and PNP transistors.  An NPN transistor consists of two n-type semiconductor materials separated by a thin layer of p-type.  In contrast, a PNP transistor consists of two p-type semiconductors separated by a thin layer of n-type.

 Transistors are used in modern vehicles for engine control, power inverters for electric drives, and electronic systems including power windows.  These are a major player in the electric vehicle market.