I just had a really stupid thought, after finishing reading the article. So, the electron is an elementary particle, right? Compared to the proton, the electron is "simple", yes? Despite this difference in complexity, an electron has a charge of -e and a proton has a charge of +e. They are exactly complementary regarding charge (if I am understanding right, I am not a smart person). my question is... why? why must pr…
Charge is quantized. You cannot have just any amount of electric charge. An electron has three elementary units of negative charge, quarks have -1 and 2. Whether it's a coincidence that proton and electron charge are of the same magnitude (and the neutron is neutral) is another question, but at the elementary level you don't have that much choice for what the charge of a particle is.
Wikipedia suggests the quarks that make up the proton have charge ⅔e and -⅓e