A transistor is similar to a switch, which controls the flow of an electric current, but it doesn’t have any mechanical parts nor requires human interaction. A transistor is made out of N-type and P-type semiconductors, such as Silicon, Phosphorous and Boron. The N-type semiconductors are in contact on one side with the Source and on the other side Drain. The P-type semiconductors sit between the N-type semiconductors. To transfer the electrons from Source to Drain, a Gate contacts both N and P type semiconductors. By applying Voltage to the Gate, the electrons flow from the N-type semiconductors at either side, to the P-Type semiconductors and start accumulating there, creating a conductive channel from Source to Drain.
According to Moore’s Law, a transistor nowadays may not be bigger than 10nanometers wide. Transistors can be applied in mobiles, computers, TV’s and many more electronic devices.