This document discusses different types of radiation: 1. Natural radiation is radiation that exists naturally in the environment like sunlight and radiation from rocks and soil. 2. Ionizing radiation is radiation that can ionize atoms and molecules, including alpha particles, beta particles, gamma rays, and X-rays. 3. Non-ionizing radiation includes radio waves, microwaves, infrared radiation, and visible light. It does not have enough energy to ionize atoms or molecules.