Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid–gas interfaces. It includes the fields of surface chemistry and surface physics. Some related practical applications are classed as surface engineering.

Surface science is closely related to interface and colloid science. Surface chemistry can be defined as the study of chemical reactions at interfaces. Surface physics can be defined as the study of physical properties and phenomena of surfaces and interfacial regions. Colloid science studies material particles on a microscopic scale, both in terms of their properties (e.g., size) and their interactions with other particles or with their environment.