There are three commonly used temperature scales: Celsius (°C), Fahrenheit (°F), and Kelvin (K). Celsius is based on the freezing and boiling points of water, where 0°C is the freezing point and 100°C is the boiling point at sea level. Fahrenheit is mainly used in the United States, where 32°F is the freezing point and 212°F is the boiling point of water. Kelvin is an absolute temperature scale where absolute zero, the point at which all molecular motion ceases, is defined as 0 Kelvin. The Kelvin scale is often used in scientific calculations.