This simulation demonstrates the principles of crystallography by rendering a real cubic crystal lattice — simple cubic, body-centered or face-centered — and letting you dial in Miller indices (h k l) to see exactly which family of atomic planes they describe. The plane you set re-orients live to satisfy the crystallographic plane equation, a layer slider walks through successive parallel members of the same family spaced by the interplanar distance dhkl, and a lattice-parameter control ties that spacing to a real length in ångströms — the same quantity Bragg's law extracts from an X-ray diffraction pattern. Toggling the full plane family shows how many symmetry-equivalent faces a single set of indices actually represents, connecting the abstract (hkl) notation to concrete cleavage planes, growth facets and crystal habit.