Consider the infinite tiling of the plane by parallelograms. Supposes you have two copies of the tiling; one lying on top of the other. Pick up the top tiling and select any translation parallel to an edge of the parallelogram. Use this translation to shift the whole tiling one tile's width. Now set the tiling back down. The displaced tiling matches the bottom tiling perfectly! This is what we mean when we say a tiling possesses the symmetry p1.

Mathematicians say such a tiling is symmetric with respect to translation. This is such a basic and important kind of symmetry, it has a special name. These tiling are periodic.

Kali denotes this symmetry by "0". You can go to now to experiment with symmetry p1.