This chapter presents a comprehensive overview of wetting phenomena which take place at high temperatures. It relies in part on the chapter "Introduction to interfaces and diffusion", elsewhere in this volume, as a foundation. The topics addressed include: definitions of intrinsic wetting and associated quantities, wetting anomalies due to diffusion and anisotropy of solid/fluid interfaces, wetting hysteresis on real surfaces, and orders of magnitude of the energies that determine wetting in metal/metal, metal/ceramic and glass systems. At the end of this chapter some examples of evolving contact between liquid and solid metal illustrate the complexity of wetting phenomena at high temperature.