The hexagonal crystal system is one of the seven crystal systems of crystallography. All point groups, each with a three-fold rotation or roto inversion axis in four different directions, are included in the cubic system. So that several triple axes can exist in a lattice, these are inevitably formed as the diagonals of a cube. For this reason, the cubic lattice has three right angles and three axes of equal length. Accordingly, four triple axes run along the four spatial diagonals of the unit cells in cubic crystals. This results in three basic Bravais lattices for the cubic crystal system.