Detergents are surfactants or compounds that reduce the surface tension between two liquids or between a liquid and a solid by dissolving hydrophobic molecules. These water-soluble surfactants consist of a hydrophobic moiety (usually a long alkyl chain) and hydrophilic or water-soluble functional groups. Detergents are commonly used in biochemistry, cell biology, and molecular biology for cell lysis, purification of membrane proteins and lipids, protein crystallization, and reducing background staining in blot experiments.