Wetting refers to the process by which a liquid spreads across or adheres to a solid surface. This phenomenon is influenced by the interactions between the liquid and the solid, as well as the properties of the liquid itself, such as its surface tension. A common example of wetting is when water spreads on a clean glass surface, demonstrating good wetting properties. The degree of wetting can be measured using the contact angle, which is the angle formed at the interface of the liquid, solid, and vapor. A smaller contact angle indicates better wetting, while a larger angle suggests poor wetting. Factors like surface roughness and chemical composition of the solid can also affect wetting behavior, making it an important consideration in fields like coating technology and material science.