Brefily describe diffusion ?

Diffusion :  Diffusion is the process in which there is a net movement of particles of a substance from an area of higher concentration to an area of lower concentration. When a difference in concentration is present from one part of a system to another, the gradual change in concentration is called a concentration gradient. When a solute diffuses from the higher concentration to the lower one, it is said to move down the concentration gradient, or sometimes simply "downhill." After a while, the diffusing substance becomes fully dispersed and the system is said to be in equilibrium.

The size of a given particle can be as small as a molecule, or much larger. Diffusion occurs because all of the tiny particles are in constant motion due to kinetic energy, bombarding each other and rebounding in different directions. The overall net movement results in the particles becoming evenly distributed if given sufficient time.

Since the movement of particles is the result of kinetic energy, the rate of diffusion is a function of the amount of heat energy in a system. This can easily be demonstrated by filling three glasses with water, one with hot water, one with water at room temperature, and one with cold water. Drop exactly one drop of food coloring in each of the glasses of water and observe in which glass the food coloring diffuses the fastest to become evenly colored.

Brownian movement refers to the vibration and oscillation of microscopic particles, which is observable under the light microscope using India ink.