Chemical Vapor Deposition (CVD) is a process used to deposit thin films of material onto a substrate by reacting a gas mixture containing one or more volatile precursors in a furnace or reaction chamber. The gas mixture is usually heated to a temperature that causes the precursors to decompose and react, resulting in the deposition of a thin layer of material on the substrate. CVD is used to produce films of high purity and uniformity, making it a popular choice for a variety of applications, such as semiconductor device fabrication, optical coating, and wear-resistant coatings.