There are numerous methods employed in the measurement of temperature. Measurement of temperature is so crucial that it is the most evaluated process variable within industrial settings. Controlling of temperature is depended on the ability to measure it. Sensors help in measurement of temperature and therefore enables control it. Although different sensors use different techniques in obtaining temperature readings, they usually involve conversion of temperature to electric signals. The variation between sensor types is very significant. They differ in sensing element, range of temperature, method of calibration, and how contact is made. The most common casings for temperature sensors are made of metal and plastic. They indicate change in temperature using conditioning circuits.