Transistor - Short essay

 A transistor, or triode is a electronic component used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually as discrete Components, but many more are found embedded in integrated circuits.

According to the structure, the transistor can be divided into: BJT, SCR, TRIAC, MOSFET, IGBT, and etc.

According to the electrical polarity (positive and negative), the transistor can be divided into: n–p–n, p–n–p (BJTs); n-channel, p-channel (FETs).