2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39840These lectures start with an elementary introduction to the subject of magnetic monopoles which should be accesible from any physics background. In the Weinberg-Salam model of electroweak interactions, magnetic monopoles appear at the ends of a type of non-topological vortices called electroweak strings. These will also be discussed, as well as recent simulations of their formation during a phase transition which indicate that, in the (unphysical) range of parameters in which the strings are classically stable, they can form with a density comparable to topological vortices.19 pages, Les Houches lectures, NATO-ASI on Topological defects and the non-equilibrium dynamics of symmetry breaking phase transitions, Feb. 99High Energy Physics - Phenomenologytext