A central black hole is surrounded by a geometrically thin accretion disk, with relativistic jets launched along the rotation axis. The broad-line region (BLR) occupies sub-parsec scales, while the dusty torus begins at radii of order ∼0.1–0.3 pc. The region within dashes highlights the characteristic fueling radius R_fuel ∼ 10³–10⁴R_g, corresponding to the interface between the outer accretion flow and the BLR/torus structure. Regulation of accretion at these radii sets the viscous timescale of the flow and enables rapid transitions from radiatively efficient thin disks to advection-dominated states on Myr timescales. The figure is AI generated.