This book, which constitutes the first English edition of the French bestseller 'Introduction à la science des matériaux', fits into a global and unified vision of this discipline. A unified teaching in Materials Science is essential, particularly since in recent years, empiricism has strongly been shaken by the intensity of scientific innovation in this area. This work fits well in this global vision. Its exposition is well balanced between fundamental notions and applications and illustrated with concise tables and well-chosen illustrative examples. The didactic approach of this book is perfectly suited to engineering students, as well as physicists or chemists who are not specialized in materials science but who, nevertheless, wish to be aware of this discipline. The work should also be much appreciated by specialists in a particular field of materials science wishing to have a global view on the subject and to position their activity in a wider context. It will be equally very useful to those who left the University benches more than ten years ago. Three main subjects are considered in this work : 1. A basic description of the main classes of materials (metals, ceramics and organic polymers). 2. A concise study of structural imperfection in crystals, phase equilibria and transitions introducing the concept of alloys and a description of microstructures. 3. An analysis of materials behaviour under mechanical constraints and during rupture, and also their physical properties. A concise description of those physical properties which are the most important for the materials science engineer is equally given in this work. It is completed by a study of degradation and corrosion as well as a description of the main composite materials and an introduction to nanomaterials and nanostructured materials.