I'm trying to get a handle on what magnetism really is. I know that charge in motion generates a magnetic field. I know that objects and particles can be permanent magnets when the magnetic fields of their elementary particles "line up." But how do stationary elementary particles have the own individual magnetic fields? I've heard some people make the case that magnetism is just electrostatic forces with special relativity taken into account. Is that true? I've heard that electricity and magnetism are the same thing. Some people say there is a clear distinction between the two. Which is it?

I know that charged particles can exist as monopoles and magnetism requires two poles. But what is at the poles? What makes the poles negative and positive? The answer I'm expecting is that the magnetic dipole moments at the poles line up to make them either north or south. But what is actually happening there? What would happen if you took away one of the poles? What are you left with? In electrostatics we work with charged particles, positive and negative. But magnetic monopoles haven't been proven to exist. I know that's why the magnetic field is defined differently than the electric field, but it doesn't conceptually mean anything to me. With the magnetic field being defined as the velocity vector of a moving charged particle when the force acted on it is 0, it's almost seems like it's just completely made up to describe something we observe, but don't really understand. But what are we observing? What is the observed difference between electricity and magnetism?

The top commenter of this thread, Chris White, makes the argument that magnetism is just electrostatic forces with special relativity taken into account.

http://physics.stackexchange.com/questions/65335/how-do-moving-charges-produce-magnetic-fields

But several comments down Francisco Muller refutes him, and even if this were true, it doesn't account for the magnetism of individual stationary elementary particles.

At this point I'm completely lost. How is electricity and magnetism different? What is magnetism really?