2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/79314These are expanded notes of four introductory talks on A-infinity algebras, their modules and their derived categories.30 pages, expanded version, sketches of proofs added, references updated, final version to appear in Homology, Homotopy and ApplicationsRings and AlgebrasAlgebraic TopologyK-Theory and Homology18E30, 16D90, 18G40, 18G10, 55U35text