Abstract: The single quantity responsible for the continuing unrest and activity of the Sun is its tangled and dynamic magnetic field. It produces many fascinating phenomena, including changes in the Sun's radiative output, which has been invoked as a driver of the Earth's climate and a contributor to global change. In this talk an overview of the magnetic field of the Sun will be given and a few recent advances in our knowledge will be presented. Brief descriptions of the Sunrise and Solar Orbiter missions will also be provided. In the second half of the talk, measurements and magnetic field-based models of solar irradiance (brightness) variability will be outlined and the question will be addressed to what extent did and does the Sun influence the Earth's climate.