Celsius (°C)
The Celsius scale, indicated by °C, was devised in 1742 by Swedish astronomer Anders Celsius. His original version set 0° at water’s boiling point and 100° at its freezing point, but this arrangement was later inverted to match present-day conventions. Modern definitions relate Celsius directly to the Kelvin scale, with 0°C corresponding to 273.15 K. Today, Celsius is the most commonly used temperature scale around the world, featuring in weather reports, cooking, healthcare, and industry. Its straightforward connection to the freezing and boiling points of water makes it especially user-friendly and accessible.
Fahrenheit (°F)
The Fahrenheit scale, denoted as °F, was established in 1724 by Daniel Gabriel Fahrenheit, a physicist of Polish-German origin. Initially, he based 0°F on the freezing point of a saltwater mixture and set 96°F near average human body temperature. The system was later revised so that pure water freezes at 32°F and boils at 212°F under standard atmospheric conditions. Fahrenheit continues to be the primary temperature scale for everyday purposes in the United States and some Caribbean regions, especially for weather, cooking, and household measurements. While most countries have shifted to Celsius, Fahrenheit remains popular in the U.S. due to tradition and its compatibility with customary units.