A temperature sensor is a device used to measure the temperature of an environment, object or system. Temperature sensors are used in a variety of applications, ranging from monitoring the temperature of a refrigerator to controlling the emissions of a car engine. Temperature sensors come in many different types, but the most common types are thermistors, thermocouples, RTDs and thermometers. Each type of temperature sensor has its own unique advantages and disadvantages. In general, thermistors are the most common type used due to their high accuracy and low cost. RTDs and thermocouples are typically used for higher temperature accuracy and glass thermometers are traditionally used for low cost, low accuracy applications.