Diffusion can be described as the net motion of molecules from a region of a higher concentration, down to a region of a lower concentration along the concentration gradient. The concentration difference between two regions is known as the concentration gradient. Diffusion occurs in a wide range of areas such as plants, human body, and chemical experiments.
Hence, this concept is studied in many different areas of science including biology, physics, and chemistry. Diffusion occurs primarily because the fluid molecules (liquid or gas) happen to be in constant random motion with respect to each other. Though diffusion is mostly defined for gases.
