Quantum mechanics is a fundamental theory for understanding nature at the microscopic level, describing the behavior of particles and atoms with a mathematical rigor that has revolutionized physics. This book guides students and enthusiasts through a practical and in-depth learning journey, with numerous solved and commented exercises to reinforce concepts and develop calculation skills and critical reasoning. It begins with essential mathematical reminders, covering the fundamentals of the theory, key examples such as the double-slit experiment and the photoelectric effect, and the formalism of operators and Hilbert spaces. Classical quantum systems are analyzed, including the particle in a potential well, the harmonic oscillator, spin, and multi-particle systems with Pauli's exclusion principle. The text also addresses approximation methods and time evolution, with chapters dedicated to quantum measurements, interpretations, and advanced mathematical tools. Each chapter concludes with exercises designed to foster a solid and lasting understanding, making it ideal for university study or exam preparation.