This document defines and discusses five main types of pollution: air, water, noise, land, and radioactive. It provides details on the causes and effects of each type of pollution as well as some methods for prevention and avoidance. The types of pollution are defined as the contamination of the atmosphere, bodies of water, excessive unwanted sound, degradation of earth's surface, and introduction of radioactive materials into the environment, respectively. The document stresses that pollution poses threats to human health, other living organisms, and natural environments.