Diffusion is nothing but the movement of molecules from it's higher concentration to loyer concentration.
The sreading out and mixing of aone substance into another substance due to the motion of its particles is called diffusion.
Brownian motion :
The zig-zag movement of small particles suspended in a liquid or a gads is called Brownian motion.Brownian motion tells us that the particles are tiny nature and the particles of a matter are constantly moving.
The Characteristics Of Matter That Are Demonstrated By Diffusion Are : 
1. The matter of the solids and liquids and the gases are made of many tiny tiny particles. 

2. Diffusion process is super easy in the gases and it is medium in the liquids and in the solids it's little difficult to see because the particles in the solids are tightly packed. 

3. The diffusion process means movement of particles in different medium or the same medium.