Linked from
The 13 pages that link to Thermocouple, each with the reason it gives.
SensorBroader topic: It converts temperature differences directly into a measurable voltage.
Thermoelectric effectRelated: It turns the Seebeck voltage into a practical temperature measurement.
KilnRelated: It supplies temperature readings to many kiln controllers and monitoring systems.
AutoclaveRelated: Thermocouples measure temperatures in the chamber and within challenging loads.
ConstantanRelated: Constantan forms the negative leg of several common thermocouple types.