Publisher Summary This chapter introduces the rock coatings and discusses the scope of this field. Coatings on rocks are the earliest phenomena known to be studied by humans. Prehistoric artists used rock coatings as a blackboard for engraving motifs. Ancient cultures took advantage of rock coatings in major stone works. Rock coatings are ubiquitous, whether the cultural or natural landscapes are observed. Stone faces on older historic buildings are altered by the development rock coatings. Modern construction leaves long-term scars because of the disturbance of rock coatings. The rock coatings in semiarid, arid, or hyperarid climates cover more than three percent of the Earth's surface. The sophistication of chemical and physical data has increased over the centuries. The rock coatings are accretions on top of the rock. In most cases, rock coatings are not directly derived from the underlying rock. The formation of weathering finds and rock coatings are distinct phenomena, although they are in direct physical juxtaposition.