Smart materials are materials that can change their properties in response to external stimuli, such as temperature, light, or pressure. These materials can adapt to their environment, making them useful in various applications, including engineering, medicine, and consumer products. For example, shape-memory alloys can return to a predetermined shape when heated, while piezoelectric materials generate electricity when subjected to mechanical stress. The ability of smart materials to respond dynamically allows for innovations in design and functionality. They are increasingly used in fields like robotics, where they can enhance movement and flexibility, and in architecture, where they can improve energy efficiency by adjusting to environmental conditions.