The states of matter are solid, liquid and gas.  These states are described according to the movement of the atoms in each.  In the solid, the atoms are in fixed positions relative to the other atoms present.  In a liquid, the atoms are able to move, but maintain close proximity to each other.  In the gaseous state, the atoms have no or little attraction to each other, bounce off each other and the container in which they are held.  The movement of the atoms in the gaseous state is considered perpetual.  In fact, a colloid is a solid particle suspended in the air (or other gas) according to the movement of the atoms present.  Spouseinbox and I volunteer in the nursery at church once a month.  We had five charges present which illustrated the movement of atoms in a gaseous state in a much better fashion than I have done here.