Temperature measures the degree of thermal energy present in a substance or environment, which is a measure of how hot or cold that substance is. The common units for temperature include:
- Celsius (°C): A scale where water freezes at 0°C and boils at 100°C under standard atmospheric conditions.
- Fahrenheit (°F): A scale commonly used in the United States, where water freezes at 32°F and boils at 212°F.
- Kelvin (K): The SI unit of temperature where absolute zero (the point where molecular motion stops) is 0 K, water freezes at 273.15 K, and boils at approximately 373.15 K.
In scientific contexts, Kelvin is often preferred, especially in calculations involving gas laws and thermodynamics.