The book includes a number of new data obtained in recent years, in particular material relating to the recently discovered new structures in spiral galaxies: giant anticyclones, cyclones and slow bars. New methods for the detection of these structures are described. Types of vertical motions of stars and gas in the galaxies, whether due to the presence of spiral arms, or hose instability are discussed. An important place is given to modern numerical methods for describing the dynamics of galaxies, stellar as well as gas components. Algorithms of numerical models and a number of important results are presented.