Animation showing the effect of the forces between point charges. Charges are represented by a + (positive) or - (negative). Opposite charges attract each other, as seen when the + and - particles are placed near each other. Similar charges, whether both positive or both negative, repel each other. Electric charge is a fundamental property of many particles, for instance the electron, which by convention has a charge of -1. The interaction of charges is described by electromagnetism, one of the four fundamental forces of nature.