Designed for newcomers to the field of toxins and is intended to show how proteins work and how they can be used in research. Describes all aspects of the biology of toxins, including their synthesis and secretion from the bacterial cell. Their travels to and into the target host cell, and their modes of attacking the host cell machinery. Illustrates how bacterial toxins, each of which has distinct individual properties, often share mechanisms of secretion, membrane transport and enzymatic action.