Book excerpt: Many chemical substances or compounds - organic or inorganic, natural or synthetic - are not used in their pure form. In order for the active ingredient to be most effective or to obtain the ideal delivery form for the market, the actual synthesis and purification steps are followed by formulation to give end products that range from powders, agglomerates, and granules to suspensions, emulsions, microemulsions, microcapsules, instant preparations, liposomes, and tablets. Formulation combines colloid and surface chemistry with chemical process engineering; sometimes it consists of a simple mixing operation, sometimes it requires an entire series of rather complicated engineering procedures such as comminution, dispersion, emulsification, agglomeration or drying. This book covers basic physico-chemical theory as well as its applications in the chemical industry for the production of pharmaceuticals, agrochemicals, pigments and dyes, food, detergents, cosmetics and many other products; it also provides chemists and chemical engineers with the necessary practical tools for the understanding of the structure/ activity relationship.