Understanding solar activity and solar flares remains one of the most important unsolved problems in S/T research. In recent decades the rapid expansion in data gathering, particularly from satellites and in the radio domain, has led both to a greater understanding and to a better appreciation of the complexity of the problem. The basic causes of solar activity are now understood in broad terms. The convective zone beneath the solar photosphere is responsible for differential rotation and for the generation of magnetic fields, whose rapid emergence through the surface creates an active region. A solar flare represents the sudden release of energy stored before the flare in the coronal region of the sun's atmosphere. Energy may be stored as the free energy of a current-carrying magnetic field. The basic requirement of all flare models or magnetic field configurations is that storage of energy must be in a metastable state: stable to small perturbations but unstable to large perturbations, which lead to the impulsive release of stored energy. The different flare models are characterized by specific magnetic field configurations in the corona, and by the explosive reconnection of magnetic fields. The theoretical magnetic field configurations can be subjected to observational tests using intensity and polarization maps made with the VLA. The high spatial resolution available with the VLA and the centimeter wavelengths at which the VLA operates are ideally suited for determining the magnetic field structures of the flaring region. In particular, using radio waves of different wavelengths, one can explore different levels of the sun's atmosphere. Radio observations are also unique in that they provide important information on the strength of the magnetic field in flaring regions.
