The main purpose of these articles is to introduce the concept of the magnetic dipole which will turn out to be crucial in our later article “Stern-Gerlach experiment.” Nevertheless, if you are impatient and want to jump into “Stern-Gerlach experiment” as soon as possible, you can go ahead and read it without reading these four articles as I explain there the concept of magnetic dipole needed for “Stern-Gerlach experiment” in a light manner. Nevertheless, if you want a firm basis, you would need to read “Magnetic dipole.”