It is now over thirty years since a method was first described for the pyrolysis of hydrocarbons to form thin film diamond. We are now entering a new phase, in which potential applications of this unique material are driving improved understanding of diamond synthesis, better control of both phase purity and structural perfection, and engineering advances that will reduce the cost and increase the deposition rate. In this highly competitive area, researchers from many countries have contributed to our knowledge base, and there are several established international conferences concentrating on diamond thin films. This book brings together some of the key components in what is an exciting scientific and technical challenge: to establish diamond as an engineering material that will revolutionise operations in optics, mechanics and electronics. The sequence of papers in the book moves from fundamental studies of the deposition process, the surface structure of diamond and its stability, and the nucleation of diamond on a foreign substrate, through the current capacity for achieving epitaxial quality films, to the characterisation of diamond quality. The final section describes some of the variety of applications, and their requirements, that are being introduced to potential users.