Temperature scales are systems used to measure temperature, with the most common being the Celsius, Fahrenheit, and Kelvin scales. The Celsius scale is based on the freezing and boiling points of water, set at 0°C and 100°C, respectively. The Fahrenheit scale, primarily used in the United States, sets the freezing point of water at 32°F and the boiling point at 212°F. The Kelvin scale is used mainly in scientific contexts and starts at absolute zero, the point where molecular motion stops. In this scale, water freezes at 273.15 K and boils at 373.15 K. Each scale serves specific purposes in everyday life and scientific research.