This volume presents a multi-disciplinary approach to the physical mechanisms which structure the shape, evolution and fate of the Galaxy. It contains 4 panel sessions (the recording transcripts of the galactic 'tertulias'), an introductory historical overview on the Galaxy research, 17 reviews, and the proceedings of more than 50 oral and poster contributions. This book is not a new edition of a previous volume but it is in some way related to the book "The Formation of the Milky Way" (1995; Cambridge University Press), which contains the proceedings of the first IAA-IAC-University of Pisa meeting, held in Granada ten years ago, on the formation of the Milky Way, (see Shore's introduction). Where many other books focus their attention on singular galactic components or specific driving forces, this title provides a wide overview on the gaseous and stellar components and on the physical mechanisms which maintain the dynamical equilibrium of such a complex system as the Galaxy. The book, intended for graduate students and researchers, provides a valuable overview on the different physical mechanisms which drive the galactic gas-stars feedback.