This unit of temperature is still used customarily in the United States.
Definition: 0°F is the coldest temperature achieved by using an ice and salt mixture, and 100°F is set at the temperature of the human body. On this scale, the freezing point of water turned out to be about 32°F and the boiling point about 212°F.
1°F equals 5/9°C. To convert a temperature in °F to the Celsius scale, first subtract 32° and then multiply by 5/9. In the other direction, to convert a temperature in °C to the Fahrenheit scale, multiply by 9/5 and then add 32°. The unit was defined by the German physicist Fahrenheit.

The lowest possible temperature that can be obtained, at which all molecular motion discontinues. The unit is written as 0 K or 0 Kelvin, named after William Thomson, who developed the scale and became Lord Kelvin in 1892.
The analogous temperature in other units is:

(K) The SI unit of temperature.
Definition: One Kelvin is 1/273.16 of the difference between the triple point of water (at exactly 273.16 K) and absolute zero.
The triple point of water is the temperature at which water can exist simultaneously in the gaseous, liquid, and solid states. Absolute zero is the temperature at which all molecular motion discontinues.
0 K is according to -273,15° Celsius and -459° Fahrenheit.