Many courses on modern quantum field theory focus on the formulation and application of field theory, leaving topics related to symmetry underdeveloped. This leads to students often having an incomplete understanding of symmetries. Filling this gap, this book sheds light on various aspects of symmetry in field theory. The text presents a broad selection of important topics, including constraint theory, generalized Pauli-Villars regularization, the measure approach to anomalies, zeta function regularization, and anomalous gauge theories.