While the ideal gas law deals with macroscopic quantities of gas, the kinetic molecular theory shows how individual gas particles interact with one another. The kinetic molecular theory contains a number of statements compatible with the assumptions of the ideal gas law. It is worthwhile to list them here:
The amazing thing about the kinetic molecular theory is that it can be used to derive the ideal gas law. Such a derivation links the microscopic claims of the kinetic molecular theory to the very visibly macroscopic behavior of the ideal gas law. The derivation is beyond the scope of this note, but you should ask your instructor to show you if you're interested.