Solar flares and coronal mass ejections (CMEs) are prominent signatures of the explosive release of energy stored in the coronal magnetic field. At some point during the evolution of a magnetic field configuration the stored energy is converted into heat, kinetic energy of bulk flows (ejecta) and energetic particle populations. Observations with increasing sensitivity and temporal resolution have shown that the corona varies on a broad range of time and length scales. It is now thought that the apparently steadily heated corona itself may owe its existence to similar explosive phenomena of interactions between plasmas and magnetic fields. The manner in which magnetically stored energy is converted to other forms, and prominently to energetic particle populations, is clearly of central importance for coronal physics.