system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: what is an electron made of?

ELI5: I'm wondering what is the 'material' composition of any fundamental particle? If electrons (and other particles) are simply energy, and are not made of matter, then how does matter exist? I know mass and energy are interchangeable but I'm unable to wrap my head around how different elementary particles, which are made up of energy give rise to different elements that we can touch, feel, see etc. How does nothing (energy but not material) give rise to something that has distinct properties?

Edit: thank you all for your time and explanations. I found them very helpful! Much appreciated.
gpt
We don't know. We consider them "fundamental" because it appears (as far as we can tell) that they aren't "made" of anything simpler. There are hypotheses that fundamental particles are made up of something simpler (such as strings in String Theory) but nothing with any empirical evidence.

They *are* made of matter if simply for the tautological reason that we have defined matter to be the thing that gives them mass.

The properties of the fundamental particles arise from differences in mass, charge, and spin.

The differences in elements come from the numbers of protons, neutrons, and electrons, with emphasis on how the electrons are organized about the nucleus. This determines how stable it is and the kinds of bonds it forms with other elements.