  Coherent states have three main properties: coherence, overcompleteness and
intrinsic geometrization. These unique properties play fundamental roles in
field theory, especially, in the description of classical domains and quantum
fluctuations of physical fields, in the calculations of physical processes
involving infinite number of virtual particles, in the derivation of functional
integrals and various effective field theories, also in the determination of
long-range orders and collective excitations, and finally in the exploration of
origins of topologically nontrivial gauge fields and associated gauge degrees
of freedom.
