State changes refer to the transformation of matter from one physical state to another, such as from solid to liquid or liquid to gas. These changes occur due to variations in temperature and pressure. For example, when heat is applied to ice, it melts into water, demonstrating a change from the solid state to the liquid state. Common types of state changes include melting, freezing, evaporation, and condensation. Each process involves energy transfer, either absorbing or releasing heat. Understanding state changes is essential in fields like chemistry and physics, as they explain how substances behave under different conditions.