Shape-memory alloys are special materials that can return to a predetermined shape when heated above a certain temperature. These alloys are typically made from a combination of metals, such as nickel and titanium, which give them unique properties. When deformed at lower temperatures, they can "remember" their original shape and revert back when warmed. These materials are used in various applications, including medical devices, actuators, and robotics. Their ability to change shape in response to temperature makes them valuable for creating devices that can adapt to different conditions, improving functionality and efficiency in many fields.