Book excerpt: The aim of the book is to introduce the reader to the kinetic analysis of a wide range of biological processes at the molecular level. It is intended to show that the same approach can be used to resolve the number of steps in enzyme reactions, muscle contraction, visual perception and ligand binding receptors that trigger other physiological processes. Attention is also given to methods for characterizing these steps in chemical terms. Although the treatment is mainly theoretical, a wide range of examples and experimental techniques are also introduced and an historical approach is used to demonstrate the development of the theory and experimental techniques of kinetic analysis in biology.