Hey everyone, I'm new to these forums. Being an electrical engineering major, most of my teachers aren't very concerned with the "physics" side of things. I'm hoping I can gain some insight on Maxwell's equations. When first stating Gauss's Law for Magnetism, the only reason my electromagnetics text gives for this is that all magnetic field lines close upon themselves. Therefore, the flux due to the B field over a closed surface is zero. This makes perfect sense to me, and I thought that this fact would be true for the H field as well. However, when deriving magnetic boundary conditions, if you assume that the flux due to the B field is always zero, it is impossible that the flux due to the H field is always zero as well. If your Gaussian surface is in free space or in one medium, then both equations can be true, but not if the volume enclosed by your Gaussian surface contains an interface. My confusion may be a result of not understanding exactly what the difference between B and H is on a fundamental level (I know the constitutive relationships). What is so special about the B field? Why isn't the flux due to the H field always zero?