This Symposium was held at Surfer's Paradise, Queensland, Australia, from 7 to 11 September 1973. The Organizing Committee, chaired by J. P. Wild, consisted of A. Boischot, A. Bruzek, J. T. Jefferies, G. Newkirk, T. Takakura, and V. V. Zhelez­ nyakov. We are indebted to the Local Organizing Commettee, chaired by S. F. Smerd and including R. G. Giovanelli, R. E. Loughhead, N. G. Seddon, K. V. Sheridan, and J. P. Wild, for advice in preparing this volume as well as for the smooth arrangement of the sessions. In addition, the session chairmen and reporters are to be thanked for their assistance in preparing the recorded discussions. It is a pleasure to thank Mrs R. Toevs and Mr A. Csoeke-Poeckh of High Altitude Observatory for assistance in editing these Proceedings. The financial aid for the Symposium afforded by the International Astronomical Union, the Ian Potter Foundation of Melbourne, and the Sunshine Foundation of Melboume, as well as generous assistance of the CSIRO Divisions of Physics and Radiophysics is gratefully acknowledged. That the solar corona is not a quiescent plasma was first fully appreciated through the discovery of solar radio bursts thirty years ago. Since that time intensive re­ search has uncovered a vast variety of coronal disturbances and revised our con­ cept of this region of the solar atmosphere to that of a dynamic medium undergoing continuous expansion, constantly evolving under the influence of underlying photo­ spheric activity, and frequently traversed by transient phenomena.