Sensors are the eyes and ears of machines and plants. They are needed to accurately monitor the production process and are extremely crucial for Factory Automation. As we have moved from Industry 1.0 to Industry 4.0, the importance and advancement of sensor technology has increased multifold. Industry 4.0 defines a vision of smart products exchanging data via the internet. Pressure, temperature, flow, displacement, current, voltage, humidity, force, angle, speed and acceleration are some of the variables that are measured using sensors and are used for monitoring the process. A sensor can be a pressure gauge, pressure switch, pressure transducer, temperature meter, flow switch, Mass flow meter, proximity sensor, ultrasonic sensor, photoelectric sensor, encoder, positioning system and so on and so forth.