Armature winding refers to the arrangement of wire coils within the armature core of an electric motor or generator. It is responsible for producing the rotating magnetic field or electromotive force necessary for the motor or generator's operation. The armature winding is typically made of insulated copper or aluminum wire and is designed to carry current and interact with the magnetic field to generate mechanical motion or electrical energy. It plays a crucial role in the conversion of electrical energy into mechanical energy or vice versa in the motor or generator system.