An electron carries a negative charge. The charge of a single electron is referred to as the unit electrical charge, which is equal to -1.6 x 10^-19 coulomb. Electrons are one of the three fundamental subatomic particles that make up atoms, along with protons and neutrons. Protons are positively charged, while neutrons have zero charge or are neutral. The negatively charged electrons revolve around the nucleus in a fixed circular path called an orbit or shell.