In crystallography, short range order refers to the regular and predictable arrangement (i.e. crystalline lattice) of atoms over a short distance, usually with one or two atom spacings. However, this regularity described by short-range order does not necessarily apply to a larger area.^[1] Examples of materials with short range order include amorphous materials such as wax, glass and liquids^[2] as well as the collagen fibrils of the stroma in the cornea.^[3]

Besides ordering of atoms, short-range ordering of vacancies are also possible. Example of systems with short-range ordering of oxygen-vacancies include oxygen-deficient stoichiometries of the superconductors YBa₂Cu₂O_7−δ, Nd_2−xCe_xCuO_4−y; as well as perovskites and novel bismuth sillenites.^{[4][5][6][7][8]}