Quantum mechanics is a branch of physics that deals with the behavior and properties of particles at the smallest scales, such as atoms and subatomic particles. It describes the fundamental principles that govern the nature of matter and energy at the quantum level. Unlike classical physics, which primarily deals with macroscopic objects, quantum mechanics introduces concepts such as wave-particle duality, superposition, and entanglement, which can be counterintuitive and differ from our everyday experiences. In essence, quantum mechanics provides a framework for understanding the probabilistic nature of particles and their interactions, offering a more accurate description of the microscopic world.