Electronic introduction
Electrons are negatively charged subatomic particles. It can be free (not belonging to any atom) or it can be bound by a nucleus. The electrons in the atom are present in a variety of radii and spherical shells that describe the energy level. The larger the spherical shell, the higher the energy contained in the electron.
In electrical conductors, current is generated by the independent movement of electrons between atoms, and typically from the cathode to the anode of the electrode. In semiconductor materials, current is also generated by moving electrons. But sometimes, it is more illustrative to think of current as an electron-deficient movement from atom to atom. An electron-deficient atom in a semiconductor is called a hole. Typically, holes "move" from the positive electrode of the electrode to the negative electrode.