A thermopile is a device that converts thermal energy into electrical energy. It consists of multiple thermocouples connected in series or parallel, which generate a voltage when there is a temperature difference between their junctions. This makes thermopiles useful for measuring temperature or detecting heat. Thermopiles are commonly used in various applications, such as in infrared thermometers and gas appliances for safety and efficiency. They can also be found in thermal imaging cameras and temperature sensors, where they help monitor heat levels without direct contact with the object being measured.