The advances in solar, planetary, and extrasolar science employing polarimetric tools are far-reaching, and the pace of discovery is accelerating rapidly. In the last three decades, the emphasis of solar polarimetry has been to achieve simultaneously high spectral, spatial, and temporal resolution for all four Stokes parameters. In the field of stellar polarimetry the developments have been equally impressive, in allowing the detection and surface mapping of magnetic fields across the Hertzsprung–Russell diagram. This volume, arising from IAU Symposium 305, is devoted to sharing advances in science, data analysis, modeling, and instrumentation between solar and non-solar polarimetry communities. Given the relevance of polarimetric measurements to many aspects of astrophysics, the techniques and physical interpretations addressed within the book will be of interest to a wide audience of researchers and advanced students, in addition to those from solar and stellar communities.