The degree Celsius
The degree Celsius (°C) is the SI-derived unit of temperature on a scale where 0 °C is the freezing point of water at standard pressure and 100 °C is the boiling point. Defined in 1742 by Anders Celsius (originally with the scale inverted) and refined repeatedly since, it shares its size of degree with the Kelvin: a change of 1 °C is identical to a change of 1 K. It is the everyday temperature unit almost everywhere outside the United States.