This book discuss new recent and exciting results in the field of accretion and ejection physics onto supermassive black holes at the center of active galactic nuclei (AGN). Through a uniform and systematic analysis of the X-ray spectra of a large sample of Seyfert and radio galaxies observed with the XMM-Newton and Suzaku satellites, here we report the statistical significance of blue-shifted Fe K absorption lines at energies higher than 6 keV. A curve of growth analysis and detailed modeling are reported as well. This allows to estimate the general parameters of the associated ultra-fast outflows (UFOs). They are found to be common, highly ionized, massive and with mildly-relativistic velocities. Their location is very close to the accreting supermassive black hole, consistent with being accretion disk outflows. Their mechanical power is also high enough to significantly affect the surrounding environment, therefore contributing to the feedback between the central black hole and the host galaxy. These results have been recently featured in conjunct press releases by NASA, the European Space Agency and the National Italian Institute for Astrophysics.