Thermal spray is defined as a process, in which feedstock materials are heated to a molten or semi-molten state by either electrical or combustion energy and projected in a form of droplets toward a substrate. On the substrate, sprayed particles are flattened and rapidly quenched to solidify to form coatings with peculiar lamellar structures. In this article, a short introduction of thermal spray technology has been given, covering topics such as the principles of thermal spraying process, fundamental processes in coatings formation, structural characteristics of thermal sprayed coatings, and recent developments in the feedstock materials and spray processes. Emphasis was given to deformation and solidification processes of single sprayed particles, microstructure-property relationships of sprayed coatings, and stress generation in coatings.