The rich low energy structure at the edge of fractional quantum Hall °uids provides an ideal arena
for the study of strongly correlated low dimensional systems. The chiral Luttinger liquid model
o®ers a general and powerful framework for describing these edge excitations. Here we review recent
theoretical progress, focusing on edge state transport. The chiral Luttinger model is ¯rst introduced
for the integer quantum Hall state at ¯lling º= 1 and the Laughlin states at ¯llingº=1=m(m
odd), where there is only a single edge mode. For the fractional quantum Hall e®ect this edge
mode is a strongly correlated Luttinger liquid, which leads to a number of striking predictions for
the transport behavior through a point contact. For º =1=3 the point contact conductance is
predicted to vanish asT
4
at low temperatures, whereas for resonant tunneling a universal lineshape
with width scaling to zero asT
2=3
is predicted. A recent experiment by Milliken, Umbach and
Webb gives evidence for this striking behavior. For hierarchical quantum Hall °uids, the edge is
more complicated, consisting of multiple modes. In this case impurity scattering at the edge is
argued to play an essential role, allowing the di®erent modes to equilibrate with one another. In
the absence of such equilibration the Hall conductance can be non universal. We show that edge
impurity scattering leads to a new disorder dominated phase. The low energy physics in this phase is
described by a new, exactly soluble, ¯xed point. Various experimental predictions and implications
which follow from this exact solution are described in detail.