The solar cycle in photosphere and corona reflects the internal dynamics on the Sun. According to the modern understanding the observed behavior of solar activity is related to the dynamo process in convection zone and photosphere and it is closely connected with the evolution of the coronal structures. The observational data from ground and space allow us to investigate the solar cycle as a complex phenomenon and to clarify the most important features such as polar magnetic field reversals, non-uniform distributions of the solar activity complexes and fine structure of the solar cycle.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html