A colloidal suspension is a mixture where tiny particles, known as colloids, are dispersed throughout a liquid or gas. These particles are larger than molecules but too small to settle out or be seen with the naked eye. Common examples include milk, fog, and paint, where the dispersed particles remain evenly distributed. In a colloidal suspension, the particles do not settle due to their small size and the interactions with the surrounding medium. This stability is often enhanced by factors like Brownian motion, which keeps the particles in constant motion, preventing them from clumping together and settling at the bottom.