Much of the art of confectionery is based on the science of crystallization. In the case of hard candy, toffee, brittle, and caramels, the object is to prevent crystallization in order to create the organic “glass” that is the defining quality of these products. Table sugar (sucrose) is crystalline in nature, and, unless steps are taken to prevent it, sucrose reverts to a crystalline state. Understanding and controlling crystallization is the basis of the entire field of confectionery. Therefore, it is important for the professional to have a basic comprehension of the crystallization process and how to control it. Fortunately, no advanced degree in physics or chemistry is required in order to grasp the fundamentals of sugar crystallization. Once a professional understands the key concepts, he or she can manipulate the formulas and procedures to get precisely the desired results. The following sugar-cooking procedure illustrates the principles involved. Each of the steps is designed to help prevent crystallization.