The essential parts of thin films are described in the chapter entitled “Fundamentals of Thin Films.” Consequently, this chapter focuses on the different deposition techniques, the criteria for selecting the material, the growth mechanism, and the morphology of the film. Studying these factors helps to uncover how thin films work and how they can be designed for certain uses. The discussion involves an analysis of methods of film depositions—physical and chemical, impact of different materials on the film characteristics, and complex processes that define the growth of films and their structure and properties. In a way which details the broad nature of the field, this chapter seeks to lay down strong conceptual basis for comprehending the imperative role and the versatility of thin films in modern technology and diverse industrial applications.