Abstract
This chapter is a brief introduction, for mathematicians, to genes, cellscell and cancercancer. It provides general descriptions of the biological phenomena that are the subject of the mathematical applications developed in later chapters. More specific information relevant to each application is given at the beginning of the section containing the application. No knowledge of biology or chemistry is assumed beyond that learned in high school and forgotten due to disuse. Many biological details are omitted for lucidity. Readers familiar with the biological topics in this introduction may proceed directly to the later chapters.