Temperature is a measure of the average kinetic energy of the particles within a substance. Kinetic energy is the energy of motion, so the faster the particles are moving, the higher the temperature.

Here's a breakdown:

* Solids: Particles in solids are tightly packed and vibrate in place. Higher temperatures mean faster vibrations.

* Liquids: Particles in liquids are more loosely packed and can move around each other. Higher temperatures mean more frequent and energetic collisions.

* Gases: Particles in gases are spread far apart and move freely. Higher temperatures mean faster and more erratic movement.

Important Note: Temperature is an average. Even within a substance at a certain temperature, individual particles will have a range of speeds.