This chapter deals with atom-wall interaction occurring in the "long-range" regime (typical distances: 1-1000 nm), when the electromagnetic fluctuations of an isolated atom are modified by the vicinity with a surface. Various regimes of interaction are discussed in an Introductory part, from Cavity Quantum ElectroDynamics modifications of the spontaneous emission, to Casimir effect, with emphasis on the atom-surface van der Waals interaction, characterized as a near-field interaction governed by a z-3 dependence. The major part of the Chapter focuses on the experimental measurements of this van der Waals interaction, reviewing various recent techniques, and insists upon optical techniques, and notably selective reflection spectroscopy which is particularly well-suited when excited atoms are considered. A review of various experiments illustrates the specific effects associated with a resonant coupling between the atomic excitation and surface modes, from van der Waals repulsion to surface-induced resonant transfer, and with anisotropy effects, including metastability transfer induced by a quadrupole contribution in the interaction. The effects of a thermal excitation of the surface -with a possible remote energy transfer to an atom-, and of interaction with nanobodies -which are intrinsically non planar- are notably discussed among the prospects.