The basic structural features of the solar chromosphere and corona are identified either with physical properties of the plasma or with properties of the energy input. It is argued that those properties identified with plasma physics should be relatively invariant whereas those identified with the energy input should vary from star to star. Energy input (ergs cm/sup -3/ s/sup -1/) to the solar atmosphere has at least two maxima, one in the low chromosphere and a second in the corona. It is assumed that the same is true of other stars.