Symmetry - Symmetry refers to visual elements mirrored to the other half of the surface (or form, in the case of 3-dimensional work). Symmetry requires an axis by which the mirroring occurs. This axis can be vertical (left-right mirroring), horizontal (top-bottom mirroring), or diagonal. Rotational symmetry refers to a variation in symmetry that allows for more than one mirroring of visual elements around a central point, rather than an axis. A kaleidoscope is an example of rotational symmetry.
Symmetry (vertical axis)
Symmetry in architecture: reconstruction of the Parthenon
Symmetry (diagonal axis)
Jack-in-the-Pulpit No. IV, 1930
(note: symmetry does not require completely identical mirroring)
Radial Symmetry (horizontal and veritcal axis)