Abstract: The modern approach to symmetries in terms of defect operators supported on manifolds on which they only depend topologically. For continuous symmetries, at the classical level, this follows from Noether’s theorem. We will discuss their quantum version, which needs regularization and certain contact terms. For holographic theories, we propose a holographic description of the operators implementing continuous global symmetries that are dual to superstring gauge fields in terms of non-BPS D- branes, and consider further extensions.