On the basis of mutual interactions or behavior of several materials in an external magnetic field, the materials are dividing in three basic categories.

(i) Diamagnetic materials: Diamagnetism is the intrinsic property of each material and it is generated due to mutual interaction among the applied magnetic field and orbital motion of electrons.

(ii) Paramagnetic materials: In these substances the inner orbits of atoms are incomplete. The electron moves are uncoupled, consequently on giving a magnetic field the magnetic moment generated because of spin motion align in the direction of magnetic field and induces magnetic moment in its direction because of which the material gets feebly magnetized. In these materials the electron number is odd.

(iii) Ferromagnetic materials: In few substances, the permanent atomic magnetic moments have strong tendency to align themselves even without any external field.

These materials are called as ferromagnetic materials.