celsius / centigrade

0°C and 100°C are arbitrarily placed at the melting and boiling points of water and standard to the metric system

fahrenheit

Fahrenheit established 0°F as the stabilized temperature when equal amounts of ice, water, and salt are mixed. He then defined 96°F as the temperature "when the thermometer is held in the mouth or under the armpit of a living man in good health."

kelvin

Based upon the definitions of the Centigrade scale and the experimental evidence that absolute zero is -273.15°C

rankine

A °F version of the Kelvin scale. Based upon the definitions of the Fahrenheit scale and the experimental evidence that absolute zero is -459.67°F