A crystal is defined as a solid material whose internal atomic arrangement possesses a high degree of periodicity and long-range order. This characteristic order results in the formation of repeating structural units known as a crystal lattice. The geometry of this lattice dictates the material's physical properties, such as its cleavage planes, optical behavior, and electrical conductivity. Crystallography, the study of these structured solids, involves analyzing how these repeating arrangements define the material's symmetry and internal forces. These highly ordered structures are foundational to various technological applications, providing the basis for the manufacture of semiconductors, specialized optical components, and high-strength materials.