I will present some results from individual and statistical analyses of AGN X-ray spectra I performed during my thesis work. On the individual approach, we constructed a sample of local Seyfert galaxies and studied their absorption characteristics simultaneously in the optical and in the X-rays. On the statistical approach, we developed a new method to obtain an average rest-frame X-ray spectrum and applied it to a large sample of distant AGN in order to measure the average Fe emission from medium to high redshifts.