  With its unique data samples at energies of 3.8--4.6 GeV, the BESIII
experiment made a significant contribution to the study of charmonium and
charmonium-like states, i.e., the XYZ states. We review the results for
observations of the Zc(3900) and Zc(4020) states, the X(3872) in e+e-
annihilation, and charmonium psi(1^3D_2) state, as well as measurements of the
cross-sections of omega chi_cJ and eta J/psi, and the search for e+e- to gamma
chi_cJ and gamma Y(4140). We also present data from BESIII that may further
strengthen the study of the XYZ and conventional charmonium states, and discuss
perspectives on future experiments.
