What is the SI unit for temperature?

The SI unit for temperature is Kelvin. The Kelvin scale is an absolute temperature scale that starts at absolute zero, the point where all thermal motion ceases. It is essential in scientific contexts because it relates directly to the kinetic energy of particles; therefore, it's the preferred scale in physics and many areas of chemistry.

Unlike Celsius and Fahrenheit, which are relative temperature scales that are based on defined points such as the freezing and boiling points of water, the Kelvin scale provides a universal standard that is crucial for calculations in thermodynamics and other scientific fields. Each increment on the Kelvin scale is equivalent to the increment on the Celsius scale, which allows for conversion and provides a scientifically useful framework for understanding temperature in relation to energy and phase changes.

Other temperature scales like Rankine and Fahrenheit serve different applications, often in engineering and meteorology, but they are not used as the standard unit of temperature in the International System of Units (SI).