Crystal, also known as crystalline solid, is a material whose constituents are arranged in a highly ordered microscopic structure. It forms a crystal lattice that extends in all directions. The branch of science, which studies crystals, its formation, and the bonding and arrangement of atoms in crystalline solids is known as crystallography. Crystal structure is the ordered arrangement of atoms, molecules and ions in a crystal. It is used in materials science to characterize different materials and phase identification. X-ray crystallography is a method that determines the molecular conformations of large biomolecules, particularly nucleic acids such as RNA and DNA, and protein. Neutron crystallography is used in refining structures obtained by X-ray methods. Electron crystallography uses transmission electron microscope to determine the arrangement of atoms in solids. This book provides comprehensive insights into the field of crystallography. Most of the topics introduced herein cover new techniques and the applications of crystallography. This book will serve as a reference to a broad spectrum of readers.