2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/186732I review recent progress on the connection between string theory and quantum chromodynamics in the context of the gauge/gravity duality. Emphasis is placed on conciseness and conceptual aspects rather than on technical details. Topics covered include the large-Nc limit of gauge theories, the gravitational description of gauge theory thermodynamics and hydrodynamics, and confinement/deconfinement thermal phase transitions.38 pages, 24 figures. Lectures given at the RTN Winter School on "Strings, Supergravity and Gauge Theories" at CERN on January 15-19, 2007High Energy Physics - Theorytext