Fahrenheit is a unit of temperature in the imperial system of units. It is equal to 9/5 degrees Celsius; however, the two scales have different values for the freezing point of water. It is used as the official temperature scale in the USA, along with a few other Caribbean countries. The system marks 32°F as the freezing point of water, and 212°F as the boiling point of water.
It was originally developed by physicist Daniel Gabriel Fahrenheit who set 0°F as the stable temperature of a mix of ice, water and salt. He then set 32°F as the temperature of an equal mix of water and ice, and set 96°F to the approximate human body temperature. After his death, it was recalibrated to what it is today.