  We show that a Coulomb gas Vertex Operator representation of 2D Conformal
Field Theory gives a complete description of abelian Hall fluids: as an
euclidean theory in two space dimensions leads to the construction of the
ground state wave function for planar and toroidal geometry and characterizes
the spectrum of low energy excitations; as a $1+1$ Minkowski theory gives the
corresponding dynamics of the edge states. The difference between a generic
Hall fluid and states of the Jain's sequences is emphasized and the presence,
in the latter case, of of an $\hat {U}(1)\otimes \hat {SU}(n)$ extended algebra
and the consequent propagation on the edges of a single charged mode and $n-1$
neutral modes is discussed.
