In chemistry, a "leaving group" refers to an atom or group of atoms that can depart from a molecule during a chemical reaction. This process is crucial in reactions such as nucleophilic substitution, where the leaving group is replaced by a nucleophile. A good leaving group is typically stable after it leaves, allowing the reaction to proceed smoothly. Common examples of leaving groups include halides like chloride (Cl⁻) and bromide (Br⁻), as well as water (H₂O). The ability of a leaving group to detach is influenced by its stability and the strength of the bond it forms with the rest of the molecule.