Magnetism is a physical property produced by the motion of electric charge, resulting in attractive and repulsive forces between objects. The motion of electric charges causes a magnetic field, which allows objects to attract or repel each other. The most familiar effects of magnetism occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. The direction of the electrons spin determines the direction of the magnetic field. If the majority of electrons in an atom spin in the same direction, a strong magnetic field is produced. The phenomenon of magnetism is mediated by the magnetic field, which imparts magnetic forces on other particles that are in the fields. The alignment of unpaired electrons produces a permanent magnet, which is the result of ferromagnetism. Diamagnetism is caused by the orbital motion of electrons within atoms creating tiny current loops, which produce weak magnetic fields. When an external magnetic field is applied to a material, these current loops tend to align in such a way as to oppose the applied field. Paramagnetism occurs when a material becomes magnetic temporarily when placed in a magnetic field and reverts to its nonmagnetic state as soon as the external field is removed.