Hi all! I am learning superconductivity for the first time. As i saw, the supercurrent of some material is governed mainly by electron pair! Now my question raises here, how do those electron pairs form? What are their features compared to single electrons? Here is what i guess: "at very low temperature (T <Tc), the valence shell is fully filled and no electron can have enough thermal energy to make it excited up to the conduction band. And according to Pauli principle, the number of possible electrons that can live together with opposite spins is limited to 2. Now i guess that the conduction (supercurrent) is driven by these pairs of electrons that are bound together and hence the conduction is within the valence band. what do you think?" Please, i need your help to understand.