An electron has a negative charge exactly equal and opposite to that of a proton. Note: the charge is exactly equal, even though the proton has a far greater mass than the electron (some 2000 times heavier in fact, not that there has to be of necessity any relationship between mass and charge).
Now that’s strange since the electron is a fundamental particle but the positively charged proton is a composite particle, made up of a trio of quarks (as it the neutron with no net charge). The proton has two quarks each with a positive 2/3rds charge (up quark) and one quark with a negative 1/3rd charge (down quark) for an overall balance of one positive charge. (The neutron on the other hand has one up quark with a positive 2/3rds charge and two down quarks each with a negative 1/3rd charge, for an overall balance of zero charge – neither positive nor negative.)
Now you might suggest that an electron might be a fusion of a trio of down quarks, each with a negative 1/3rd charge, except the electron, again, isn’t a composite particle, and the mass is all wrong for that scenario. If an electron were a composite of a trio of down quarks, each with a minus 1/3rd charge, the electron would be thirty times more massive than it is – not something particle physicists would fail to take notice of.
Further, the force particle that governs the electron is the photon; that which governs the quarks inside the proton and the neutron is the gluon, which further differentiates the two things – quarks and electrons. In any event, if you could have a composite particle of a trio of negative 1/3rd down quarks, if that were the case, and it is the case, and it’s called the Negative Delta, you’d also need a composite particle that’s the fusion of a trio of positive 2/3rds up quarks for an overall charge of plus two. To the best of my knowledge there is only one such critter in the particle zoo and it’s called the Doubly Positive Delta. I’m sure you’ve never heard of these Delta particles, which goes to show how much bearing or impact they have on life, the Universe, and everything.
In case you were wondering, there would be an anti-quark of minus 2/3rds charge, and an anti-quark of a positive 1/3rd charge, to yield an anti-proton and an anti-neutron. The anti-proton would of course have an equal and opposite charge to the anti-electron (which has a formal name – the positron). So things are equally as mysterious in the realm of the anti-world.