The standard unit for measuring temperature is degrees Celsius (°C) in most countries, although degrees Fahrenheit (°F) is commonly used in the United States. The Celsius scale is based on the freezing point of water at 0°C and the boiling point at 100°C under standard atmospheric conditions. The Kelvin scale (K) is another important temperature measurement used mainly in scientific contexts, where 0 K represents absolute zero, the theoretical point where all molecular motion ceases. Each scale serves different purposes, with Celsius and Fahrenheit commonly employed in everyday situations, while Kelvin is used in scientific research and discussions regarding thermodynamics.