Solubilization increases the solubility of poorly water-soluble solute molecules in an aqueous solution of surface active agents or surfactants due to which a thermodynamically stable solution is formed. When surfactants are added to water at low concentrations, they tend to orient at the air–liquid interface. As additional surfactant is added, the interface becomes fully occupied and the excess molecules moves into the bulk of the liquid. At still higher concentrations, the molecules of surfactant in the bulk of the liquid begin to form oriented aggregates or micelles. The concentration of surface active agent at which micelles occur is called “critical micelle concentration.” The water solubility of the solute increases with the concentration of the micelles. Examples of solubilizing agents are tweens, spans and sodium lauryl sulphate (SLS). Surface active agents having hydrophilic–lipophilic balance (HLB) values higher than 15 are better solubilizing agents.