This document discusses various diseases including infectious diseases, water-borne diseases, and cancer. It begins with an introduction to diseases and defines different types. It then focuses on infectious diseases, describing causes such as bacteria and viruses. Common infectious diseases and their transmission are listed. Water-borne diseases and their causes from contaminated water are also reviewed. Finally, cancer is discussed, including causes from genetic mutations and carcinogens. Preventative measures are suggested for infectious diseases, water-borne diseases, and reducing cancer risk.