2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46541We give an introduction to the heavy-quark effective theory and the $1/m_Q$ expansion, which provide the modern framework for a systematic, model-independent description of the properties and decays of hadrons containing a heavy quark. We discuss the applications of these concepts to spectroscopy and to the weak decays of $B$ mesons.45 pages, 11 figures; Lectures presented at the 34th International School of Subnuclear Physics: Effectives Theories and Fundamental Interactions, Erice, Italy, 3-12 July 1996High Energy Physics - Phenomenologytext