We'll discuss defects, of which a link in a 3-manifolds is an example, and stratificaitons more generally.  We will discuss factorization homology over defects, and characterize such in terms of E_n-algebras and module data therefor.  Augmentations lend to examples of such module data.  The collection of deformations of an augmentation of an E_n-algebra A organize as a formal E_n-stack, the Maurer-Cartan formal moduli problem MC_A.  Poincare'/Koszul duality relates the sigma-model with target MC_A and factorization homology of A.