2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/214668We discuss corks, and introduce new objects which we call plugs. Though plugs are fundamentally different objects, they also detect exotic smooth structures in 4-manifolds like corks. We discuss relation between corks, plugs and rational blow-downs. We show how to detect corks and plugs inside of some exotic manifolds. Furthermore, we construct knotted corks and plugs.43 pages, 61 figures, published versionGeometric Topology57R55; 57R65text