19. CONCLUSIONS

Many years ago, Lindblad (1974) stated that ``It would be of the utmost importance for our understanding of density waves if we could identify the different resonance regions in the galaxies observed.'' We have never been closer to such a goal as we are now. We have shown in this review that the case for identifying observed rings and pseudorings in normal galaxies with dynamical orbit resonances associated with a bar is very strong. We have illustrated many different examples and highlighted the best and least understood cases. We have also shown that many rings are incredible star formation laboratories, and that in some galaxies a ring is the only place where major star forming events are taking place. Sophisticated modeling of individual galaxies is now necessary to further address the problems outlined in this review. The Hubble Space Telescope also has the capability to elucidate the structure in the ILR regions of barred galaxies in unprecedented detail. But the main interest of ringed and barred galaxies is what these objects tell us about how galaxies evolve. Identifying the locations of the main resonance regions in barred galaxies is one of the most important steps in understanding the dynamics of these objects.

We thank our many colleagues for their helpful discussions and collaborations over the years of research on galaxy structure and dynamics that led to this review. We also thank the authors who allowed us to use illustrations from their published works.