Defines and differentiates between matter and energy, highlighting how matter occupies space and has mass, while energy relates to work and causing change. It explores various forms of energy and how they are measured or converted, citing examples like hydroelectric, solar, and nuclear power. The text also categorizes systems based on their interaction with the environment and introduces key physical properties like mass, volume, temperature, pressure, and density, explaining their definitions, how they are measured, and their significance in various contexts, including health and practical applications.