Write a short note on transistor

A transistor is a semiconductor device that transfers a weak signal from low resistance circuit to high resistance circuit. In simple words, what it means is that it regulates and amplifies electrical signals such as voltage or current. 
Transistors are special because they allow you to control how much current flows through a circuit. This can be achieved by controlling the voltage across two of the transistor leads. Each transistor has three leads.
A transistor is an influential little invention that changed the course of history for computers and all electronics. A transistor consists of two PN diodes that are connected back to back. It has three terminals that are named emitter, base and collector. John Bardeen, William Shockley, and Walter Brattain were scientists at the Bell Telephone Laboratories. The idea for transistors arose when they were working on an idea that used a field effect to control the current in a semiconductor.