Colloid
A heterogeneous mixture in which particles between 1 and 1000 nm are dispersed through a continuous medium.
Unit
nm
In depth
Colloidal particles are too small to settle under gravity or be removed by ordinary filtration, yet too large to form a true solution. They scatter light, undergo Brownian motion, and are stabilised by surface charge or by an adsorbed layer that prevents them coalescing.
Examples in the real world
Milk, fog, blood, paint, jelly and whipped cream are all colloidal systems.