The particle character of matter

Almost all matter that we know around us, is built up of mixtures.

Mixtures can be separated in components, up to pure substances.

Those pure substances in turn are built up of one kind of equal particles: molecules or atoms or ions.

Pure substances (if not already elements) can be decomposed into elements.

And an element is built up of only one kind of atoms.

Every substance is built up of 'particles': molecules, macromolecules or (complex / simple) ions. In special cases, a substance may be built up of atoms.
All those particles can differ in size, molecular mass, charge or in (a)polar character and in cinetic energy (movement, vibration).

Heating up a substance (= adding energy) means that every particle receives cinetic energy (movement energy). This particle will increase its movement. This can be done in a dislocation of the particle, but also in more vibration.
To that phenomena is not really a limit; the particle always can increase movement, that is: get hotter, up to millions of grades Celcius. The movement becomes every time heavier.
Attention: very likely something will happen to that substance.

Cooling a substance has a limit. During cooling the movement decreases. Eventually the particle has no movement anymore; it is still. Less movement than no movement is impossible. Even the lightest particles, with hardly any mutual attraction forces, will become still at sufficient low temperature.
If in a gas, the particles first become a liquid (there is still movement), and finally a solid is made with a (molecular) lattice.
Less movement than no movement is impossible and a lower temperature than the minimum temperature does not exist = 0 K(elvin) (= -273ºC)
You may say that temperature is a measure for movement of the particles.