Cationic surfactants are a class of surface-active agents whose hydrophilic groups acquire a positive charge upon dissociation in aqueous solution. Their molecular structure typically comprises hydrophobic long chains combined with positively charged nitrogen or phosphorus atoms in the hydrophilic group, with quaternary ammonium compounds being the most prevalent type. These surfactants exhibit unique bactericidal, antistatic, and softening properties through strong electrostatic adsorption with negatively charged surfaces. They effectively disrupt microbial cell membranes, neutralize static electricity on fibers, and form lubricating molecular films at interfaces. Major varieties include alkyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, and benzalkonium chloride. They are extensively used in fabric softeners, hair conditioners, disinfectant wipes, antistatic agents, and biocides. Important considerations include their general incompatibility with anionic surfactants and the potential ecotoxicity of certain variants, necessitating careful selection based on application requirements.