this book gives an up-to-date introduction to the structure, physical properties and applications of quasicrystalline alloys. it covers quasiperiodic tilings and the determination and modelling of the atomic structure of quasicrystals. the electronic properties, determined from measurements of the partial electronic density of states and the calculation of the electronic structure, play a key role in this introduction, as does an extensive discussion of the determination and simulation of the atomic dynamics. for the application of these aperiodic crystals, defects are a critical issue. thus the book also presents a detailed treatement of the study of defects in quasicrystals by high resolution electron microscopy and ion channeling, as well as computer simulations of defects and fracture in decorated tilings.