Surface Active Agents (surfactants) are vital components in biological systems, form key ingredients in consumer products and play an important role in many industrial processes. For example, cell membranes owe their structure to the aggregation of surfactants known as lipids which form a major component of the membrane. Other natural surfactants occur in the digestive system, in the lungs, and even in such substances as crude oil. Man-made surfactants are used in a wide range of domestic and industrial products and processes. In addition to detergents and personal care products, surfactants have found uses in almost every branch of the chemical industry as well as in several other industries. These include dyestuffs, fibres, mineral process­ ing, oil field chemicals, paints, pesticides, pharmaceuticals and plastics. Surfactants are versatile materials which are manufactured in a huge variety of forms to suit all of these applications. As a result of their importance, the technical literature on all aspects of surfactant behaviour is now very extensive. Surprisingly, however, the treatment in textbooks has been somewhat fragmented, often in the form of conference proceedings or edited, multi-authored works, both lacking in continuity.