A coil spring is a mechanical device made from a flexible material, typically metal, that is wound into a helical shape. It is designed to store and release energy when compressed or stretched. Coil springs are commonly used in various applications, including automobiles, furniture, and industrial machinery, to provide support and absorb shock. These springs work based on Hooke's Law, which states that the force exerted by a spring is proportional to its displacement. Coil springs can be found in different sizes and strengths, allowing them to be tailored for specific uses, such as in suspension systems or toys.