How do particles generally move in diffusion?

In diffusion, particles move randomly until they are evenly distributed across a space. This process occurs due to the inherent kinetic energy of the particles, causing them to move in various directions and collide with one another. As a result of these movements, particles tend to spread from areas of higher concentration to areas of lower concentration, which is driven by the concentration gradient. This random motion continues until an equilibrium is reached and the particles are evenly distributed in the available space.

The randomness of particle movement is a fundamental aspect of diffusion, distinguishing it from other processes, such as directed movement against or with a flow, which would not capture the essence of how diffusion operates. In diffusion, there are no physical barriers that control the movement, and particles are not restricted to moving solely through specific pathways like water. The focus is purely on the natural tendency of particles to disperse throughout the available area without a directed flow.