2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/52073We review the construction of the $D$-branes at finite temperature as boundary states in the Fock space of thermal perturbative closed string. This is a talk presented by I. V. V. at Common Trends in Cosmology and Particle Physics June 2003, Balatonfured, Hungary.Prepared for the workshop Common Trends in Cosmology and Particle Physics, Balatonfured, HungaryHigh Energy Physics - Theorytext