Book excerpt: Aperiodicity and Order, Volume 1: Introduction to Quasicrystals deals with various aperiodic types of order in quasicrystals as well as the basic physics of quasicrystalline order and materials. Questions about the nature of order and the order of nature are addressed. This volume is comprised of six chapters; the first of which introduces the reader to icosahedral coordination in metallic crystals, with emphasis on the structural principles of metallic materials that are crystalline and may be expected to carry over to aperiodic materials. The discussion then turns to short- and long-range icosahedral orders in glass, crystals, and quasicrystals. The origins of icosahedral order are explained, and the physical properties of icosahedral materials are described. The chapters that follow focus on the metallurgy of quasicrystals, the crystallography of ideal icosahedral crystals, and stability and deformations in quasicrystalline solids. The book concludes with a discussion on symmetry, elasticity, and hydrodynamics in quasiperiodic structures. A pedagogical review of continuum elastic-hydrodynamic theory for quasicrystals and related structures is presented. This book is intended primarily as an introduction for new students in the field and as a reference for active researchers.