Caption: Maxwell's equations plus Lorentz force constitute the basic theory of classical electromagnetism which is the macroscopic limit of quantum electrodynamics which in turn is a special limit of the theory of everything (TOE) one assumes.

You need classical electromagnetism for, e.g., electric motors and electric generators, but quantum mechanics (though maybe NOT full quantum electrodynamics???) to make your cell phone work.

The image shows Maxwell's equations in their differential equation form (more precisely, their partial differential equation form) and in MKS units form.

Yours truly considers classical electromagnetism an emergent theory because it is exact in the classical limit and in all macroscopic practical applications. It may or may NOT be a possible theory in a universe with different fundamental physics from our own.

You can buy a t-shirt:

And God said ... and there was light.