  Foa a given local ring, we study the fiber cone of ideals with analytic
spread one. In this case, the fiber cone has a strucure as a module over its
Noether normalization which is a polynomial ring in one variable over the
residue field. One may then apply the structure theorem for graded modules over
a graded principal domain to get a complete descriptionof the fiber cone as a
module. We analyze this structure in order to study and characterize in terms
of the ideal itself the aritmetical properties and other numerical invariants
of the fiber cone as multiplicity, reduction number or Castelnuovo-Mumford
regularity.
