Quantum measurement is a process in quantum mechanics where the properties of a quantum system, such as position or momentum, are observed. When a measurement is made, the system's wave function collapses, resulting in a definite outcome. This phenomenon highlights the difference between classical and quantum physics, as the act of measurement affects the system being observed. The concept of quantum measurement is closely related to the Heisenberg Uncertainty Principle, which states that certain pairs of properties, like position and momentum, cannot be precisely measured simultaneously. This principle emphasizes the inherent limitations in our ability to know the exact state of a quantum system before measurement occurs.