In this talk, Vincent will present a general overview on what we learnt from Planck on the properties of Galactic dust and magnetic fields. The Planck survey has provided a global overview on the structure and statistical properties of magnetic field at large scales through the observation of dust polarized emission. Interstellar dust grains behave like small spinning tops, precessing around magnetic field lines. The polarization of their thermal emission is a measure of the direction of the magnetic field projected onto the plane of the sky. Vincent will show how the 353GHz Planck channel has offered an unprecedented wealth of statistics on the properties of its ordered and turbulent components, distinct of those probed by synchrotron emission, and forced to a major revision of interstellar dust models.