Stupeň celzia °C

Today, the Celsius scale (as a minor unit of the SI system) is defined by the triple point of water, which is assigned a temperature of 0.01 °C, and by the absolute magnitude of one temperature scale degree (±1 °C) being equal to 1K.

Compared to today, the scale was originally reversed. Celsius introduced it in 1742 with two fixed points at an air pressure of 1013.25 hPa, namely 100°C for the freezing point of water and 0°C for the boiling point of water[1]. Carl Linnaeus later turned the scale around and that is why it is today defined as

0 °C for the freezing point of water
100°C for the boiling point of water.