Abstract: I present the elements of accretion-disc physics applied to active galactic nuclei. The accretion driving mechanisms are discussed, then models of geometrically-thin discs, both stationary and time-dependent, are addressed. Disc's self-gravitation in the AGN context is presented. The shapes of spectral line from accretion discs are explained in both newtonian and relativistic cases. The physics of disc's thermal and viscous instabilities is dicussed in detail and models are applied to AGN discs. Finally, the problems of thick accretion flows (ADAFs and slim discs), disc coronae, winds and jets are discussed in some detail. This is a graduate-student level lecture, not a review article