Magnetism is a phenomenon of physical science that arises due to the forces between objects brought about by the motion of electrical charges within those objects. The motion of electric charges creates a magnetic field, which exerts a magnetic force on charged particles that move within that field. A magnetic field flows from one end of an object to the other, creating a dipole with positive and negative ends.
Magnetism arises from the very structure of the atom. Each atom consists of a nucleus that contains neutral neutrons and positive protons. Negatively charged electrons are constantly in motion around this nucleus, and it is this motion that causes a magnetic field. A good example of magnetism is an electric current, which is essentially the flow of electrons. As electrons flow down a wire, a magnetic field develops around the wire.
All materials exhibit some degree of magnetic properties, though some are far more magnetic than others. The degree of magnetism is associated with the degree of mobility of a substance's electrons. Materials such as iron, in which the electrons are free to flow about in a sea around the positive nuclei, exude strong magnetic fields because there is more electron movement. Materials such as aluminum, in which the electrons are more tightly bound to the nuclei of the atoms, exude much weaker magnetic fields.