Small but mighty.
Electrons belong to a special group of particles called leptons, which are fundamental, meaning they’re not made of anything smaller. Electrons are the most familiar of them. Unlike quarks, which stick together to form protons and neutrons, electrons do their own thing, orbiting atomic nuclei and refusing to be tied down.
They carry a negative electric charge, so they interact with photons (the bosons of electromagnetism), which is where electricity, magnetism and most of our technology comes from. They’re also not only particles, they behave like waves. In the quantum world, they can be in multiple places at once, interfere with themselves, and even teleport (sort of) through quantum tunneling.