Definition:Rubik's Cube

Definition
Rubik's cube is a toy consisting of a plastic cube divided into $27$ smaller cubes, interlocking at the center cube and allowing each face to rotate independently of the others.

Each of the six faces of the main cube is colored with one of six contrasting colors. Rotating the faces of the cube causes these six faces to become mixed up.

The object of the exercise is to restore the six faces to their original single colors.