Symmetry:

In a plane, a figure has symmetry if there is an isometry, other than the identity, that maps the figure to itself.

Line Symmetry:

For each figure there is a line of symmetry such that the reflection
maps the figure onto itself.

Point Symmetry:

For each figure there is a point of symmetry such that a half turn
maps the figure onto itself.

Rotational Symmetry:

Each figure has a center and rotates the figure onto itself.

Translational Symmetry:

Translation that maps the figure onto itself.