In many diverse engineering applications the ability of liquids to wet solids affects the quality of the finished products and the integrity/reproducibility of the manufacturing processes. Some important examples of this are the production and application of paints and varnishes, the development and the optimisation of composite materials, the use of adhesives and selection of solvents for engineering materials, and the biocompatibility of medical implants. Reliable analytical data is provided via the precise evaluation of static and dynamic contact angles, the surface free energy of solids and the surface and interfacial tension of liquids. Last but not least, the recent, rapid, advanceÃ­ments in nanotechnology and biotechnoÃ­logy have been possible, only, through an exact knowÃ­ledge of wetting processes in the sub-microscopic level.