This book describes the basics and historical aspects of thin film. The introductory chapter of this book contains various aspects about thin-film deposition methods, significance of nanomaterials in the fabrication of thin film, certain fundamental characteristics of thin films (electrical, optical, and morphological), some challenges (thickness uniformity, film adhesion issues, temperature-related challenges, film defects and quality control, preparation of the surface of the substrate before deposition, etc.) faced during the formation of thin film, significance, and different types of deposition techniques along with their basic introduction, working principle, construction, merits/demerits, and also application in specific fields. This book specifically works on the techniques of thin-film deposition and role of the thin film in the formation of these deposition methods.