Here's a breakdown:

* Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. This happens because particles are in constant random motion and tend to spread out evenly over time.

* This applies to both gases and liquids, as their particles are free to move around.

For example:

* Gas diffusion: If you spray perfume in one corner of a room, the scent will eventually spread throughout the room due to diffusion of perfume molecules in the air.

* Liquid diffusion: If you drop a drop of food coloring into a glass of water, the color will gradually spread throughout the water due to diffusion of the dye molecules.