I think, the normal force is a contact force which exists in any type of contact between two objects. It may or may not be equal to the weight of the body. For eg. if you hold a rubber by pressing it against a wall, the normal reaction is equal to the force you exert and not the weight of the eraser. In fact, if the rubber is in equilibrium, it is the friction that is equal to the weight.

 

Please rate me if you like the answer.