2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10897The current status of understanding of the X-ray emission from Seyfert galaxies involves thermal Comptonization of soft photons by mildrelativistic electrons and positrons. I review observational and theoretical arguments supporting such a view, discussing current models proposed for the structure of the innermost part of the accretion flow: extended coronae, small scale flaring blobs, advection dominated accretion disks and small scale cold cloudlets.8 pages, 1 figure.ps. Latex (memsait.sty). To apper in the Proceedings of "Dal Micro al Mega Parsec: Secondo Congresso Nazionale sui Nuclei Galattici Attivi (From Micro to Mega Parsecs: Second Italian National Workshop on Active Galactic Nuclei)"Astrophysicstext