This book aims to introduce the fundamental concepts and mathematical formalism of quantum mechanics. It covers the principles of wave-particle duality, quantum states, and operators. Topics include the Schrödinger equation, Heisenberg uncertainty principle, and quantum entanglement. The book deals with applications such as quantum tunneling and the hydrogen atom. Advanced topics like quantum computing and quantum field theory are also explored. The text is suited for upper-level undergraduate and graduate students in physics.