The fundamental theoem of magnetostatic equilibrium predicts that the bipolar magnetic fields of active regions on the Sun contain tangential discontinuities as an intrinsic part of their equilibrium. It appears that rapid reconnection at these many tangential discontinuities (nanoflares) is the primary source of heat that produces the X-ray emitting corona. The X-ray corona is then a cloud of nanoflares. ¿American Geophysical Union 1990