Diffusion process

Diffusion is when something spreads out slowly from one place to another. For example, when you open a bottle of perfume and it smells strong, that smell slowly spreads out into the rest of the room as the perfume diffuses through the air. Diffusion can also happen with liquids: if you put food coloring in a glass of water, the color spreads out throughout the water as the molecules in the food coloring mix with the molecules in the water.