Electric charge
Things that have equal numbers of electrons and protons are neutral. Things that have more electrons than protons are negatively charged, while things with fewer electrons than protons are positively charged. Things with the same charge repel each other. Things that have different charges attract each other. If possible, the one with too many electrons will give enough electrons to match the number of protons in the one that has too many protons for its load of electrons. If there are just enough electrons to match the extra protons, then the two things will not attract each other anymore. When electrons move from a place where there are too many to a place where there are too few, that is called an electrical current.