This chapter fully discusses the synthesis of thin films and explains the techniques involved, namely spin coating, CVD, PVD, laser ablation, and atomic layer deposition (ALD). These are very important in the synthesis of thin films and all contribute uniquely toward the formation of high-tech materials with specific features. In the production of films on substrates, it is very commonly practiced to utilize the CVD method that comes from chemical reactions between precursors in the gaseous phase. It is very useful in the production of excellent motion pictures with few defects and outstanding uniformity. CVD is excellent for electronics and optics applications, since it can have numerous modifications-low pressure and plasma enhanced CVD, which enables depositing films at relatively low temperatures, with an enhanced control of film properties. PVD is comprised of a lot of physical deposition methods such as sputtering and thermal evaporation. In the case of PVD, the deposited materials are evaporated in a vacuum before condensation. Vacuum-induced vaporization of solid materials is followed by condensing onto a substrate in PVD. This method is well-known for producing high-performing, long-lasting coatings that improve surfaces’ mechanical and chemical characteristics. PVD is widely used in making optical coatings, ornamental finishes, and semiconductors. Applying homogeneous polymer or sol-gel thin films is the main application for the adaptable spin coating technology. Using centrifugal force, a liquid solution is applied to a substrate and quickly spun to distribute the material uniformly. Applications in microelectronics and photonics benefit greatly from spin coating’s ability to produce thin films with precise thickness.