The large Nc and chiral expansions have been used to
examine the properties and nature of resonances in
pi-pi scattering. I review some important aspects of this
problem from different viewpoints.

    Refs. Phys.Lett.B679:449-453,2009.
          Phys.Rev.D80:045023,2009.
          Phys.Rev.D81:054009,2010.