Here's the nucleus of an atom with a couple of electron orbitals going around it. Let's say the spin direction is like this. That means the direction of the magnetic field it's producing is perpendicular to the spin axes. and the way you know which direction the magnetic field is going is by using the right hand rule. So here's a picture of my right hand with the palm facing me as I draw it. My thumb is right here, sticking up. Now if I curl my fingers into the palm and leave my thumb sticking up sort of like this, my fingers are curled around this way and my thumb is sticking up. That shows the direction of the spin axis and my thumb is showing the direction of the magnetic field. That's the right hand rule.

In a material that is magnetic you have a bunch of atoms arranged and each one is oriented the same way with respect to the orbitals of the electrons. So in this case all the electrons are spinning like this and the magnetic field they produce -- each one is like this, they are all parallel to each other. Those reinforce each other and the overall effect is to produce a magnetic field in your material.

In a material that's not magnetic, you have a group of atoms like this but the spins of their electrons are all randomly oriented. So one might be like this, and another one is like that, maybe one is this way, another one goes this way, and so forth. and let's say the spin of this one is in this direction, this one could be here, this one might be like that. Just random orientations. The magnetic field produced by each atom -- this one would be like this -- see we're using the right hand rule here to figure out which direction each field is going. This would go this way. And this one is going like this. And so the net effect of each little teeny magnetic field produced by these atoms is to cancel each other out. The overall effect is you have a material that's not magnetic.