  Parker has hypothesised that, in a perfectly ideal environment, complex
photospheric motions acting on a continuous magnetic field will result in the
formation of tangential discontinuities corresponding to singular currents. We
review direct numerical simulations of the problem and find the evidence points
to a tendency for thin but finite thickness current layers to form, with
thickness exponentially decreasing in time. Given a finite resistivity these
layers will eventually become important and cause the dynamical process of
energy release. Accordingly, a body of work focusses on evolution under
continual boundary driving. The coronal volume evolves into a highly dynamic
but statistically steady state where quantities have a temporally and spatially
intermittent nature and where the Poynting flux and dissipation are decoupled
on short timescales. Although magnetic braiding is found to be a promising
coronal heating mechanism much work remains to determine its true viability.
Some suggestions for future study are offered.
