This textbook provides a pedagogical introduction to the formalism, foundations and applications of quantum mechanics. Part I covers the basic material which is necessary to understand the transition from classical to wave mechanics. The Weyl quantisation is presented in Part II, along with the postulates of quantum mechanics. Part III is devoted to advances in quantum physics. Intended for use as a textbook for beginning graduate and advanced undergraduate courses, it is self-contained and includes problems to aid the reader's understanding.