Confinement and Deconfinement in 2+1 Dimensions

I discuss the physics of confinement and deconfinement in 2+1 dimensional non-abelian gauge theories at weak coupling. I show that the low-energy dynamics is determined universally by the spontaneous breaking of the magnetic symmetry introduced by 't Hooft more than 20 years ago. The degrees of freedom in the effective theory are magnetic vortices. I give an explicit derivation of the effective low energy theory for the vortex field. Confinement in this effective theory is a very simple classical statement about the long range interaction between topological solitons, which follows (by virtue of a simple direct classical calculation) from the structure of the effective Lagrangian. I demonstrate that above the critical temperature the magnetic symmetry is restored and that this transition is identical with the deconfining phase transition.