This chapter describes some of the concepts related to surfactants and their use in consumer and industrial products. In addition, their structure and classification, the raw materials used in their production, and the unique properties they possess (because of which they are invaluable components in a wide variety of household, industrial, pharmaceutical, and food applications) are discussed. Such properties include the ability of surfactants to lower the interfacial tension that exists between two immiscible liquids (e.g., oil and water), thus promoting emulsification and wetting of the solid surfaces, which facilitates removal of the fatty/oily and particulate soils and facilitates cleaning. At the end of the chapter, the major applications in which surfactants are used are listed. These are described in greater detail in various chapters in this manuscript dealing with specific applications.