The shape memory effect is a property of certain materials, particularly some alloys and polymers, that allows them to return to a predetermined shape when heated above a specific temperature. This phenomenon occurs because the material's molecular structure changes in response to temperature, enabling it to "remember" its original form. Commonly used in applications like medical devices and robotics, the shape memory effect can be found in materials such as nickel-titanium alloys, often referred to as Nitinol. These materials can be deformed at lower temperatures and then revert to their original shape when warmed, making them useful for various innovative technologies.