Temperature indicators are devices used to measure and display temperature. They can be found in various forms, such as thermometers, thermocouples, and infrared sensors. These tools are essential in many fields, including meteorology, cooking, and industrial processes, helping to ensure safety and efficiency. Different types of temperature indicators operate on various principles. For example, mercury thermometers use the expansion of mercury in a glass tube, while digital thermometers provide electronic readings. Infrared sensors measure temperature from a distance by detecting emitted radiation, making them useful in situations where contact is not possible.