Magnetic fields in stellar atmospheres are believed to play the major role in stellar activity such as flares and atmospheric heating. However, the spatial scales on which conversion of magnetic energy to other forms takes place are small and cannot be resolved in stellar observations. Solar obse... Show moreMagnetic fields in stellar atmospheres are believed to play the major role in stellar activity such as flares and atmospheric heating. However, the spatial scales on which conversion of magnetic energy to other forms takes place are small and cannot be resolved in stellar observations. Solar observations of the magnetic fields in the atmosphere and the physical processes that lead to energy release remain our best prospect for advancing our understanding of stellar activity. This white paper summarizes the current state of observations of magnetic fields in the solar atmosphere, describes prospects for much improved measurements with new instruments, and discusses the connections to stellar science. Show less