ABSTRACT
Symmetry elements and operations are strongly related to each other but they must be well defined from the beginning. Looking in the mirror, we can see a virtual image that is exactly like us. We say the image is symmetrical to the object. e reflection of light on the mirror surface is the phenomenon that produces this symmetric image. e reflection in the mirror (mirror symmetry) is the most common meaning of symmetry. Other types of symmetry will also be discussed in this book. e reflection is the symmetry operation and the mirror is the plane of reflection, that is, it is the symmetry element.
