  We review a global analysis of meson production reactions off the nucleons by
a collaboration at Excited Baryon Analysis Center of Jefferson Lab. The
analysis is pursued with a dynamical coupled-channels approach, within which
the dynamics of multi-channel reaction processes are taken into account in a
fully consistent way with the two-body as well as three-body unitarity of the
S-matrix. With this approach, new features of nucleon excitations are revealed
as resonant particles originating from the non-trivial multi-channel reaction
dynamics, which cannot be addressed by static hadron models where the nucleon
excitations are treated as stable particles.
