ИСТИНА

Current observations allow us to consider changes of the solar-stellar activity in the evolutionary aspect. It is clear that development of active processes is determined by physical parameters, with which a star arrives to the main sequence. At birth, low-mass stars in the open cluster have a large dispersion of rotation, which decreases rapidly due to the fact that rapid rotators are slowed down more effectively. During the first 1 Gyr, the initial dispersion almost disappears. To this epoch, magnetic fields are formed that evolve in a close correlation with rotation and determine the pattern of activity over the next billions of years. Distinctions between the saturated regime of activity intrinsic to the youngest fast rotating low-mass stars and the solar-type activity when a cycle begins to form are considered. Changes in the regime of activity are discussed in the context revealing epochs of the cycle formation on stars of different spectral types. Discovery of the most powerful non-stationary phenomena like superflares on G-type stars during the Kepler mission is a challenge that outlined the new challenges to be addressed. Now it is clear that the largest superflares occur rather on fast rotators, i.e. on stars, whose activity is in saturation regime and which possess the maximal magnetic activity. Joint analysis of observations of superflares and available data on stellar magnetic fields on solar-type stars gives a chance to estimate the maximal possible energy of stellar flares and to understand their origin.