The interaction between a liquid and a solid surface is the key to understanding wetting phenomena, irrespective of whether they are static or dynamic. A very large number of natural and industrial processes rely on the delicate manipulation of this interaction. Controlled wetting is of central importance in microfluidics, mineral flotation, high speed coating, electronic display technologies, oil recovery, lubrication and plant protection.

At the molecular level, one can alter the distribution and charge of surface groups on functional surfaces, vary the number of hydrogen bonds, change molecular configuration, perform chemical grafts etc. External stimuli such as light, electric potential, heat and magnetism can lead to subtle control of wettability. Physical and chemical heterogeneity can have a major impact upon wettability, thus the clever design of surface architecture is a key element in controlling both wettability and liquid movement. When a liquid moves over a solid surface, displacing air or another liquid, the primary routes of energy dissipation must be identified if the mechanism is to be understood. Molecular events play a dominant role here, as shown through experiment, theory and simulation.