The type of magnetism you’re most familiar with (the kind that keeps magnets on your fridge) is technically known as ferromagnetism. Ferromagnets are permanent magnets—they generate their own magnetic field. Ferromagnets have unpaired electrons (so from the information in the previous question we can say that ferromagnets are paramagnetic, not diamagnetic). But ferromagnets have one additional key trait—the unpaired electron spins are all aligned in the same direction, which generates a permanent magnetic field.

Let’s go through this again from the beginning: Electrons have spin (a quantum mechanical property, but we don’t need to go that far back), and this spin generates a very, very tiny magnetic field. If all the electrons in a substance are paired, it is diamagnetic. If there are unpaired electrons, the substance is paramagnetic. If there are unpaired electrons and those unpaired electrons are aligned so that there is a “net spin” for the (macroscopic) substance, it is a ferromagnetic. Ferromagnets are the magnets you know—they stick to your fridge.