  In this paper, we study the reliability of BCS theory as a scientific
explanation of the mystery of superconductivity. It is shown clearly that the
phonon-mediated BCS theory is fundamentally incorrect. Two kinds of glues,
pairing (pseudogap) glue and superconducting glue, are suggested based on a
real space Coulomb confinement effect. The scenarios provide a unified
explanation of the pairing symmetry, pseudogap and superconducting states,
charge stripe order, spin density wave (SDW), checkerboard-type charge-ordered
phase, magic doping fractions and vortex structures in conventional and
unconventional (the high-Tc cuprates and MgB2) superconductors. The theory
agrees with the existence of a pseudogap in high-temperature superconductors,
while no pseudogap feature could be observed in MgB2 and most of the
conventional superconductors. Our results indicate that the superconducting
phase can coexist with a inclined hexagonal vortex lattice in pure MgB2 single
crystal with a charge carrier density ps=1.49*10^{22}/cm^{3}. Finally, the
physical reasons why the good conductors (for example, Ag, Au, and Cu) and the
overdoped high-Tc superconductors are non-superconducting are also explored.
