Symmetry is of interest in two ways, artistic and mathematical. It underlies much scientific thought, playing an important role in chemistry and atomic physics, and a dominant one in crystallography. It is important in architectural and engineering design and particularly in the decorative arts. This book provides a comprehensive account of symmetry in a form acceptable to readers without much detailed mathematical knowledge or experience who nevertheless want to understand the basic principles of the subject. It will be useful in school and other libraries and as preliminary reading for students of crystallography. The treatment is geometrical, which should appeal to art students and to readers whose mathematical interests are that way inclined.