  When the quantum Hall effect occurs in a two-dimensional electron gas, all
low-energy elementary excitations are localized near the system edge. The edge
acts in many ways like a one-dimensional ring of electrons, except that a
finite current flows around the ring in equilibrium. This article is a brief
and informal review of some of the physics of quantum Hall system edges. We
discuss the implications of macroscopic {\em compressible strip} models for
microscopic {chiral Luttinger liquid} models and make an important distinction
between the origin of non-Fermi-liquid behavior in fractional quantum Hall
edges and in usual one-dimensional electron gas systems.
