Quantum spin liquids are a state of matter that occurs in certain materials where the magnetic moments, or spins, of electrons do not settle into a fixed arrangement, even at absolute zero temperature. Instead, these spins remain in a fluctuating, entangled state, leading to unique properties such as long-range quantum entanglement and the potential for fractional excitations. This behavior is often observed in materials with strong interactions between spins, such as those found in certain frustrated magnets. Quantum spin liquids are of great interest in condensed matter physics because they may provide insights into high-temperature superconductivity and other exotic quantum phenomena.