Tension force is a force that is exerted equally on both ends of a cable, chain, rope, wire or other continuous object and is transmitted between the ends by that object. On a microscopic level, objects under tension have a separation between molecules that creates potential energy in their bonds.
It requires force to put an object under tension, but technically, tension itself is not a force for as long as the situation is stable. Nonetheless, physicists measure the tension in a system in units of force. Once some part of the system begins moving, such as when one end of a rope under tension is released, the potential energy between the molecules of the rope is converted to mechanical energy, and the tension is converted to force. As long as an object under tension is straight, the tension is constant for its entire length.
A force is any push or pull acting upon an object as a result of its interaction with another object. Tension forces are one of the contact forces, which are the forces present when two objects are in contact with one another. There are also non-contact forces, such as gravity, magnetic force and electrical force, which act at a distance.