What is the magnetic field made up of?

Question

What is the magnetic field made up of?

Answer 1

The magnetic field is the relativistic aspect of the electric field.  It isn't 'made up' of anything.  It is neither matter nor energy.  If you're interested, first study the electric field.  It's simpler and it's easier to visualize.

Answer 2

Magnetic fields are produced by electric currents, which can be macroscopic currents in wires, or microscopic currents associated with electrons in atomic orbits.

Answer 3

Magnetic field lines that, in turn, are pure energy. They are not matter. Photons are magnetic en electric waves intertwined.