Positive charge has always bothered me. There's no positive charge carrier; the electron carries a negative charge. We can't pump bare protons through wires--only electrons. So when we say something is positively charged, what we mean is that it has a dearth of electrons in it, because somehow a whole mess of electrons has been moved somewhere else and left there.
You can get a shock from a positively-charged object the same way you can from a negatively-charged one; it's just a question of which way the electrons are moving.
So you can combine quarks such that you get a + charge, because otherwise there'd be no protons. You can also combine them to get particles with a - charge, or to have no net charge (eg neutrons). The electron is a fundamental particle, having no innards, so it's automatically a - no matter where it comes from. Positrons are antimatter electrons so their charge is +, but you can't make an electrical circuit that uses positrons unless you are really good at mucking about with antimatter, and happen to have a lot of anti-silicon, anti-copper, anti-epoxy, and anti-solder to play with. (Hint: right now we can make anti-hydrogen a few atoms at a time, using a hyper-expensive machine and more electricity than you will personally use in your lifetime. It's not happening soon.)
We understand electromagnetism thoroughly enough that we can make individual electrons and photons sit up and beg, but how well do we understand why these things work the way they do?
I mean, magnetism--you put a hunk of iron next to a magnet, and clink they draw together. Why? I mean, forget the explanations about iron atoms being little magnets and all that; I mean where does the power come from? The magnet doesn't lose any magnetism when it pulls the iron into contact with itself. Its magnetic field doesn't diminish--in fact, if you leave it in contact long enough it'll magnetize the piece of iron. But that's not even the real question.
What the hell is the magnetic field? Where does the force come from? It's not electrons or photons circling around the poles of the magnet; it's something else.
Putting a piece of ferrous metal between the magnet and the chunk of iron immediately cancels the effect of the magnet on the iron. Almost nothing else will.
(This is why a Faraday cage will block radio signals. Photons have a magnetic component, and the cage stifles that. Grounding the cage also does for the photon's electrical component.)
There is, therefore, something circulating around that magnet, something which is channeled or blocked by ferrous material but otherwise unaffected. And we don't know what it is.
Physics says, "It's a magnetic field! Duh!" but I have never found that to be a satisfactory answer. Of course it's a magnetic field; what else would it be?
But what is a magnetic field?
--invisible lines of force, the strength is blah blah blah, the polarity etcetera, yada yada--
But what is it?
So it's just as well that I'm not a professional physicst, because I'd probably still be stuck in PHYS-101 trying to figure out why and how, which are questions no one is asking. Physics has all the formulae explaining the properties of electromagnetism and considers the rest of it to be philosophy.
I'm not sure it is.