Crystalline structures are highly ordered arrangements of atoms, ions, or molecules in a solid. These structures are characterized by a repeating pattern, which gives rise to unique physical properties. Common examples include sodium chloride and diamond, where the arrangement of particles determines the material's strength and conductivity. The study of crystalline structures is essential in various fields, including chemistry, physics, and engineering. Understanding these structures helps scientists and engineers design new materials with specific properties, such as improved durability or enhanced electrical performance. Techniques like X-ray diffraction are often used to analyze these structures at the atomic level.