  I briefly review the Regge approach to the hadron spectrum and advocate a
dynamical emergence of principal quantum number in the known spectrum of light
non-strange mesons. Further it is shown how the linear radial trajectories with
universal slope can be extended to heavy quarkonia and a qualitative string
interpretation is given. After that I discuss a recently proposed non-string
model leading to a natural appearance of linear Regge trajectories and
explaining many mass relations.
