A spring is a device consisting of an elastic but largely rigid material bent or molded into a form that can return into shape after being compressed or extended. Springs can store energy when compressed. In everyday use, the term most often refers to coil springs, but there are many different spring designs. Modern springs are typically manufactured from spring steel. An example of a non-metallic spring is the bow, made traditionally of flexible yew wood, which when drawn stores energy to propel an arrow.
Helical coil springs designed for tension
A heavy-duty coil spring designed for compression and tension
A machined spring incorporates several features into one piece of bar stock
Military booby trap firing device from USSR (normally connected to a tripwire) showing spring-loaded firing pin
A coil spring is a mechanical device which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of an elastic material formed into the shape of a helix which returns to its natural length when unloaded.
A tension coil spring
A selection of conical coil springs
Volute spring suspension on an M4 Sherman tank
Coil spring in valvetrain