"Symmetry" is a recognition of the matching-ness
of the parts of a shape.
For instance, the human body is said to have
"bilateral" (two-sided) symmetry, because the left and right halves of the body
mirror each other, as you can see in the image to the left.
But this symmetry applies only to the basic
framing structure of our bodies; much of our insides, our organs, don't match, as you can
see in the image to the right: watch the liver (brown) and the stomach (pink) change sides
when the organs are flipped.:
dotted line running down the middle of the left-hand graphic above is called "the axis of
you think of the bilateral-symmetry picture as being drawn on a sheet of transparent plastic
with a shish-kebob skewer punched through the dotted line, you could twirl the skewer (and
thus the sheet) 180° around and end up looking at the same picture, but from the other
side of the plastic sheet: