Gabriel Daniel Fahrenheit was a physicist and engineer who is best known for inventing the mercury-in-glass thermometer and for developing the Fahrenheit temperature scale. Born in 1686 in the Polish-Lithuanian Commonwealth (now Gda?sk, Poland), he later moved to Amsterdam and then to Germany, where he conducted most of his scientific work. Fahrenheit's temperature scale, which is still used in the United States and a few other countries, is based on 32 degrees for the freezing point of water and 212 degrees for the boiling point of water at standard atmospheric pressure. His contributions to the field of thermometry have had a lasting impact on the way we measure temperature.