This book sheds light on various aspects of symmetry in field theory, including constraint theory, generalized Pauli-Villars regularization, the measure approach to anomalies, zeta function regularization, and anomalous gauge theories. Unlike most field theory books, this one uses constraint theory in discussing gauge theories. The author explains how some classical symmetries are broken by anomalies and how other symmetries of the theory are spontaneously broken. He discusses all of the ideas in as simple a way as possible.