Diagnosing the radial region around the last closed flux surface out to the plasma facing components is an important task as this interface determines the plasma wall interaction. In this lecture, spectroscopic techniques for measuring the radial profiles of electron density ne(r), electron and ion temperature Te(r) and Ti(r), plasma rotation and the radial electric field as well as the hydrogenic and impurity source distribution in front of the plasma facing components and the heat and particle fluxes to these components are introduced based on the example of the TEXTOR tokamak.