Thermal effects refer to the changes in temperature and physical properties of materials when they absorb or release heat. These effects can cause expansion or contraction in solids, liquids, and gases, impacting their behavior and performance. For example, when metals like iron are heated, they expand, which can affect the fit of parts in machinery. In addition to physical changes, thermal effects can also influence chemical reactions. Higher temperatures often increase the rate of reactions, as seen in processes like combustion. Understanding these effects is crucial in fields such as engineering, chemistry, and meteorology to predict how materials and systems will behave under varying thermal conditions.