Powerful forces among atoms in solids distribute atoms one next to another in an ordered way. Each atom is bound to a balanced (still) position around which it can at the utmost oscillate to some extent. Still positions of certain atoms in a space are organized into so-called CRYSTAL STRUCTURES.
A solid body with a crystal structure is called a CRYSTAL. Because of the well ordered lattice the crystal structure has its symmetrical characteristics. They are visible in a symmetry of boundary planes of a crystal. If we observe pieces of a crystal which get smaller every time, we finally come to a CRYSTAL CELL.
The crystal cell is the smallest part of a crystal, that still has typical symmetrical characteristics of a crystal.
The great majority of chemical elements crystallizes in a CUBIC CRYSTAL STRUCTURE (the crystal cell has the shape of a cube), that appears in three varieties (see the classification).
