It is not an exaggeration to say that the single most important concept in our modern understanding of physics is that of symmetries. Whether in Newtonian mechanics, Einstein’s relativistic theories, or modern quantum field theory, symmetry principles are the essential ingredient to facilitate descriptive and predictive models of “nature”. In this Balliol Online Lecture, Dr Ling Lin, Walker Early Career Fellow in Mathematical Physics at Balliol College, will explore the basic ideas of symmetries and their unreasonable effectiveness in theoretical physics.