 Temperature

Temperature is the intensive variable thermodynamically conjugate to entropy; at equilibrium it determines the direction of heat transfer.

Temperature is a measure of the average kinetic energy of the particles in a substance. It quantifies how hot or cold an object is and is a fundamental parameter in the study of thermodynamics and physics. Temperature can influence various physical and chemical properties of materials, including their state (solid, liquid, or gas), pressure, and volume.

For scales from absolute 0 like Kelvin, is proportional to the total kinetic energy of the material.

The Boltzmann constant tells us how much energy that is, i.e. gives the slope.