Electric currents in the solar atmosphere

We review historical and modern studies pertinent to the measurements, modeling, and role of electric current in the solar atmosphere. We describe how the electric current density is computed from the vector magnetic field measurement at photospheric and chromospheric levels and how it is modeled, using Nonlinear Force- Free Field (NLFFF) extrapolations, in the solar corona. Next, the roles of electric currents in plasma dynamics and heating, energy release, and acceleration and transport of nonthermal particles are discussed. We then consider some interesting properties of electron and ion components forming electric current in a multicomponent plasma, the effect of the electric current on the Alfvén wave properties, current neutralization, and redistribution during solar flares. We discuss present theories about the origin of electric currents from subphotospheric and photospheric motions. We conclude that evaluation of electric currents in the solar atmosphere has reached a high level of maturity and that accounting for the electric current is highly important for solar physics.