The understanding of unique phase separation nature of aqueous surfactant solution is an interesting topic of research. The phenomenon of phase separation, as manifested by temperature-induced cloudiness of the surfactant solutions, is highly sensitive to the presence of different additives. This chapter describes the clouding phenomena of surfactants and their numerous applications in different fields of science. We start with a brief introduction of the clouding-assisted phase separation of surfactants. Thereafter, we address the basic principles of clouding along with the detailing about the various experimental approaches of cloud point measurement. The differences in clouding behaviour of several ionic and nonionic surfactants are highlighted. Further, we describe the impact of numerous additives on the shifting of cloud point (CP) of surfactant. The description about the effects of surfactant structures on the CP is noted. We also highlight the clouding-induced morphological switching of surfactant aggregates in solution. The temperature-dependent energetic parameters of clouding are reported from the thermodynamic viewpoint. With a view of its exercise in separation and preconcentration of compounds, we recapitulate its various applications. Finally, we make a remark on the future scope of the clouding mediated extractive approach.