Fahrenheit is a temperature scale where water freezes at 32 degrees and boils at 212 degrees. The scale was invented in the 1720s by Daniel Gabriel Fahrenheit, a German physicist who worked with thermometers and wanted a more precise way to measure heat and cold.

On a Fahrenheit thermometer, comfortable room temperature sits around 68 to 72 degrees. A hot summer day might reach 95 degrees, while a cold winter morning could drop to 20 degrees. When you have a fever, your body temperature rises above its normal 98.6 degrees.

The United States is one of the few countries that still uses Fahrenheit for everyday temperature measurements. Most other nations use the Celsius scale, where water freezes at 0 degrees and boils at 100 degrees. Scientists usually prefer Celsius because its numbers align more neatly with the metric system, but millions of Americans check Fahrenheit temperatures every day in weather reports, cooking recipes, and medical thermometers.

When someone asks “How hot is it outside?” in America, they expect an answer in Fahrenheit. Saying “It's 75 degrees” means something pleasant and mild, while “It's 15 degrees” means bundle up because it's below freezing.