Crystal structures refer to the orderly arrangement of atoms, ions, or molecules in a solid. These structures are characterized by repeating patterns that extend in three dimensions, forming a lattice. The specific arrangement influences the material's properties, such as strength, conductivity, and melting point. Different types of crystal structures exist, including cubic, hexagonal, and tetragonal systems. Each type is defined by its unique geometric arrangement and symmetry. Understanding crystal structures is essential in fields like materials science, chemistry, and mineralogy, as they help explain how materials behave and interact with one another.