Definition of spring
A spring is an elastic object used to store mechanical energy. Springs are elastic bodies (generally metal) that can be twisted, pulled, or stretched by some force.
They can return to their original shape when the force is released. In other words it is also termed as a resilient member.
A spring is a flexible element used to exert a force or a torque and, at the same time, to store energy.
The force can be a linear push or pull, or it can be radial, acting similarly to a rubber band around a roll of drawings.
The torque can be used to cause a rotation, for example, to close a door on a cabinet or to provide a counterbalance force for a machine element pivoting on a hinge.
Springs can be classified according to the direction and the nature of the force exerted by the spring when it is deflected.