Most substances are composed of molecules, which are made up of atoms, and atoms consist of atomic nuclei and electrons. Inside an atom, electrons constantly spin and orbit around the atomic nucleus. Both of these movements generate magnetism. However, in most substances, the directions of electron movements are different and chaotic, canceling out the magnetic effects. Therefore, most substances do not exhibit magnetism under normal circumstances.

Iron, cobalt, nickel, or ferrites, among other ferromagnetic materials, differ in that their internal electron spins can spontaneously align within a small range, forming a spontaneously magnetized region known as a magnetic domain.

After magnetization, ferromagnetic materials have their magnetic domains neatly aligned and oriented, enhancing their magnetic properties, thus forming a magnet. The process of a magnet attracting iron is the same as magnetizing the iron block. The magnetized iron block and the magnet's opposite poles generate an attractive force, causing the iron block to firmly "stick" to the magnet. We say that the magnet has magnetism.