Colloid is a type of mixture that scatters light and cannot be filtered. Colloids are heterogeneous mixtures with a particle size between that of the solutions and that of the suspensions: the size of the particles of a colloid is bigger than the molecules or ions of a solution and smaller than the particles of a suspension. Due to the small size of the particles in the colloids, the diluted colloids seem homogeneous, but those particles are big enough to produce the Tyndall effect, which is the dispersion of the light. Solutions do not show Tyndall effect.
