This book is about thin films; what they are, how they are prepared, how they are characterized, and what they are used for. The contents of this book not only showcase the diversity of thin films, but also reveals the commonality among the work performed in a variety of areas. The chapters in this volume are based on invited papers presented by prominent researchers in the field at a Symposium on "Thin Films: Preparation, Characterization, Applications" at the 221st National Meeting of the American Chemical Society held in San Diego, California. The coverage of the symposium was extensive; topics ranged from highly-ordered metal adlayers on well-defined electrode surfaces to bio-organic films on non-metallic nanoparticles. An objective of this book is for the readers to be able to draw from the experience and results of others in order to improve and expand the understanding of the science and technology of their own thin films systems.