I have a simple two-part question, or two simple questions. 1. What is energy? 2. What is charge? The charge I'm referring to is the charge on charged subatomic particles. And atom's charge is defined by the number of electrons and protons present in it. But an electron itself is called a negatively charged particle. We've studied about charge on an electron, so what is that? The positivity and negativity may come analogy for analogous purpose from Rutherford's experiments. That's not the point. The charge on an electron is 1.602e-19 C. What is that and what does it mean? And what causes it? Even if it means the electric field, what is it that causes that? What is this charge? I'm thinking the most common answer would be energy but even neutron has energy, it has to have energy. I would also like to know more about neutron. Neutron may be neutral in terms of charge and may be inseparable from proton but it must also contain some energy. I have never seen anyone account for the energy contained in the neutron while doing any calculation, neither have I ever seen anyone talk about it. And what happens to and with the energy of a neutron?