Surfactants play a pivotal role in a wide range of industrial, environmental, and biomedical applications due to their unique interfacial and colloidal properties. The basic ideas guiding the behaviour of surfactants at surfaces and in colloidal systems are thoroughly examined in this chapter. It explores important ideas including micellization, emulsification, surface tension reduction, and colloidal dispersion stabilisation. The main surfactant classifications—anionic, cationic, non-ionic, and amphoteric—as well as their physicochemical properties and performance in distinct conditions are addressed. The use of these qualities for applications in detergency, increased oil recovery, food processing, medicines, cosmetics, and nanotechnology is given particular attention. Furthermore, the effects of concentration, molecular structure, and environmental variables (such pH and temperature) on the stability and effectiveness of surfactant systems are explained here. A particular focus is placed on the catalytic properties of surfactants. The formation of micellar environments is explored as a means of enhancing reaction rates by increasing substrate solubility, facilitating reactant orientation, and increasing collision frequency. This chapter is a thorough resource for scholars, practitioners, and students who want to comprehend the function of surfactants in current applications and upcoming developments in this ever-evolving subject.