About the Fahrenheit scale
Fahrenheit is a relative temperature scale created by the Polish-German physicist Daniel Gabriel Fahrenheit. It is mainly used in the United States and is less common in science compared to the Celsius (or Centigrade) scale.
Fahrenheit is based on the freezing and boiling points of water at standard atmospheric pressure with 32°F at freezing point and 212°F at boiling point.
Whilst Fahrenheit is still commonly used in the United States it is important to note that most of the world relies on Celsius.
About Réaumur
Réaumur was widely used in Europe in the past but is now rarely seen. The Réaumur scale was named after the French physicist René Antoine Ferchault de Réaumur who developed it in the early 18th century. The freezing point of water is 0°Ré and the boiling point 80°Ré. This scale has been almost completely replaced by the Celsius scale.
Despite the Réaumur scale no longer being used, it had a significant impact in the history of temperature measurement.