What is the standard unit of measuring temperature?

Temperature is an intensive property that reflects the energy state of matter. Atoms and molecules are always in motion; the faster they move on average, the higher the temperature. In simple terms, temperature is proportional to the average kinetic energy of a substance’s particles.

The SI base unit of temperature is the kelvin (K), introduced by William Thomson (Lord Kelvin) in 1848. (Historically, 1 K was defined via the triple point of water at 273.16 K; today, the kelvin is defined using the Boltzmann constant.) Kelvins are common in science and technology, while Celsius (°C) is more widely used in daily life.

In the SI system, Celsius is a derived unit; its step size equals that of the kelvin (i.e., a change of 1 °C = 1 K). The Celsius scale was proposed by Anders Celsius in 1742.