Surfactants, also known as surface-active agents, have a characteristic molecular structure consisting of a hydrophilic (water-attracting) and a hydrophobic (water-repelling) part. This allows them to absorb at interfaces and reduce surface tension. Based on the ionic nature of their molecule, surfactants are classified into: anionic (negative charge), cationic (positive charge), non-ionic (no charge), and amphoteric (neutral). Surfactants act as emulsifiers, cleansing agents (detergents), foaming agents, wetting agents, solubilizers, and dispersants.