New observations by space telescopes during the last ten years have led to significant advances in understanding the nature of solar flares. X–ray and UV imaging of flare emissions have confirmed that flares are powered by the sudden release of magnetic energy associated with currents flowing in the solar atmosphere. Although many different processes have been suggested as possible trigger mechanisms, the one which seems to fit the observations best is a loss of ideal–MHD equilibrium, or stability, combined with magnetic reconnection. An ideal–MHD process by itself has the drawback that it releases a very small amount of magnetic energy, but when it is coupled with magnetic reconnection, this drawback is eliminated. Stellar flares are very likely to be fundamentally similar to solar flares in that they involve the sudden release of magnetic energy associated with currents flowing in their coronae. However, it is unlikely that they all involve exactly the same type of field configuration or the same type of trigger mechanism. What these mechanisms might be will be difficult to determine without further information on the structure of stellar magnetic fields.