Quantum mechanics is a theory that describes the dynamics at the microscopic level. It is one of three branches of mechanics in physics, alongside classical mechanics and statistical mechanics. Classical mechanics focuses on studying the motion of an object by analyzing the motion of the center of mass. Statistical mechanics, on the other hand, requires studying the motion of each particle within an object, which can be impractical due to the large number of particles involved. It deals with averages and approximations when dealing with ensembles of particles. Quantum mechanics presents a different level of understanding compared to classical and statistical mechanics.