The book reviews the knowledge obtained from ground-basedand space-borne solar flare research thus at the same timepreparing for the forthcoming mission of the satellite SolarA which will be launched in 1991. Accordinglyone section isdevoted to experiments on Solar A. The rest review boththeory and observational facts to give a physicallyrealistic picture of flares, including problems of magneticflux emergence, high energy particles in flares, heating andflows in flares, and further problems of solar activity.