A crystal lattice is a three-dimensional arrangement of atoms, ions, or molecules in a repeating pattern. This structure is fundamental to the properties of crystalline solids, such as salt or diamond. The regularity of the lattice contributes to the material's stability and determines its physical characteristics, including melting point and hardness. In a crystal lattice, each point represents a position occupied by an atom or molecule, forming a unit cell that repeats throughout the entire crystal. The specific arrangement and bonding of these particles influence how the crystal interacts with light and other substances, impacting its optical and chemical properties.