Final answer:
Temperature is a measure of the average kinetic energy of molecules; higher temperatures indicate faster movement and more kinetic energy, while lower temperatures indicate slower molecular movement and less kinetic energy.
Step-by-step explanation:
Temperature tells us about the average kinetic energy of the molecules in a sample of matter. When we say an object is 'hot,' it means its atoms and molecules are vibrating quickly, possessing higher average kinetic energy. Conversely, when an object is deemed 'cold,' it's atoms and molecules are moving or vibrating more slowly, indicating lower kinetic energy. Increasing thermal energy results in an increased temperature, while the reverse leads to a decrease in temperature. This is crucial in many applications, for example, in chemistry, where higher temperatures can cause a substance to change from solid to liquid or can accelerate chemical reactions.