A magnetic field is a special kind of material that cannot be seen or touched. The magnetic field is not composed of atoms or molecules, but the magnetic field exists objectively. The magnetic field has the radiation characteristics of the wave particles. There is a magnetic field around the magnet, and the interaction between the magnets is based on the magnetic field, so the two magnets can function without contact. A special form of matter that exists in the space around a current, a moving charge, a magnet, or a changing electric field. Since the magnetism of the magnet is derived from a current, the current is the motion of the charge, and in general, the magnetic field is produced by a change in the motion charge or electric field. From the point of view of modern physics, the ultimate component of a charge that can form a charge is electrons (with unit negative charge) and protons (with unit positive charge), so negative charges are point objects with excess electrons, and positive charges are Point objects with excess protons. The real source of the magnetic field generated by the motion charge is the magnetic field produced by moving electrons or moving protons. For example, the magnetic field generated by a current is the magnetic field generated by electrons moving in a wire.