Why is the material transparent

So the real question is not why is glass transparent,but why aren't all materials transparent?The answer has to do with the different energy levels that electrons in an atom can have.Think of these as different rows of seats in the stadium stands.An electron is initially assigned to sit in a certain row,but it could jump to a better row,if it only had the energy.As luck would have it,absorbing one of those light photons passing through the atom can provide just the energy the electron needs.But there's a catch.The energy from the photon has to be the right amount to get an electron to the next row.