Here's why:

* Temperature is a measure of the average kinetic energy of the particles within an object. Kinetic energy is the energy of motion.

* Warm objects have particles that are moving faster, on average, than the particles in cold objects.

* We perceive this difference in particle motion as a difference in temperature and describe it as warmth or coldness.

Important Note: While "warmth" and "coldness" are related to temperature, they are subjective experiences. What feels warm to one person might feel cold to another.