Particle size: 1-1000 nm (10^-9 to 10^-6 m). True solutions: < 1 nm. Suspensions: > 1000 nm. Eight types based on dispersed phase and medium (see table in main content). Lyophilic (solvent-loving): strong interaction with medium, self-stabilising, reversible (starch, gum, gelatin, proteins, soap). Lyophobic (solvent-fearing): weak interaction, requires stabiliser, irreversible (gold sol, Fe(OH)3 sol, As2S3 sol, AgI sol). Associated colloids (micelles): form above critical micelle concentration (CMC). Surfactants like soap: aggregate with hydrophilic heads out and hydrophobic tails in (in water). Kraft temperature: minimum temperature for micelle formation.