This first integrated treatment of the main ideas behind René Thom's theory of catastrophes aims to make them accessible to scientists wishing to apply the theory in their own fields of research. The mathematical basis of the theory is therefore explained with a minimum of technicalities, although some knowledge of the calculus of variables is assumed.Thom's now-famous list of seven elementary catastrophes, broadly classifying various types of discontinuous change, is elucidated, as...