What does thermal equilibrium mean from a molecular point of view?

Molecular physics studies the physical properties of bodies in various states of aggregation from the point of view of their molecular structure. According to molecular physics, a body at a particular time can be in one of three states of aggregation – solid, liquid or gaseous. In the section of molecular physics, there is a molecular-kinetic theory that explains thermal phenomena in macroscopic (that is, consisting of a set of microscopic bodies) bodies / group of bodies in terms of their molecular structure.

In the framework of molecular kinetic theory, any macroscopic body or group of bodies is called a “thermodynamic system”.

Thus, from the point of view of molecular physics, thermal (or thermodynamic) equilibrium of a body is achieved under the condition that all macroscopic parameters of the body remain unchanged – volume, pressure, state of aggregation, etc. do not change.