2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53138Article for the forthcoming Encyclopedia of Mathematical Physics, to be published by Elsevier. Covers kinks & breathers, sigma-models & Skyrmions, abelian-Higgs vortices, monopoles, Yang-Mills instantons, and Q-balls.13 pages. Article for Encyclopedia of Mathematical PhysicsHigh Energy Physics - Theorytext