This concise and systematic account of the current state of this new branch of astrophysics presents the theoretical foundations of plasma astrophysics, magneto-hydrodynamics and coronal magnetic structures, taking into account the full range of available observation techniques -- from radio to gamma. The book discusses stellar loops during flare energy releases, MHD waves and oscillations, plasma instabilities and heating and charged particle acceleration. Current trends and developments in MHD seismology of solar and stellar coronal plasma systems are also covered, while recent progress is presented in the observational study of quasi-periodic pulsations in solar and stellar flares with radio, optical, X and gamma rays. In addition, the authors investigate the origin of coherent radio emission from stellar loops, paying special attention to their fine structure. For advanced students and specialists in astronomy, as well as theoretical and plasma physics.