Nanostructured materials exhibit distinct properties by virtue of their nanoscale morphological variations, which open up endless possibilities to investigate unexplored and interesting applications. This textbook broadly covers the fabrication and characterization of nanostructured films and exploration of their gas-sensing applications. It presents the fundamentals of gas-sensing technology and a comprehensive study on smart gas sensing technology. Readers will find basics, analytical techniques, nanotechnology-enabled experimental findings, and future directions of smart gas-sensing technology at one place. Through the inclusion of up-to-date experimental knowledge of synthesis, processing, and application development, the book is suitable for academics at all levels.