Mathematical Biology is the study of medicine and the life sciences that uses mathematical models to help predict and interpret what we observe. This book describes several major contributions that have been made to population biology and to physiology by such theoretical work. We have tried to keep the presentation brief to keep the price of the book as reasonable as possible, and to ensure that the topics are presented at a level that is accessible to a wide audience. Each topic could serve as a launching point for more advanced study, and suitable references are suggested to help with this. If the underlying mathematics is understood for these basic examples. then mathematical aspects of more advanced life science preblems will be within reach.