The author surveys the theory of (regular) compactifications of locales, stressing the aspect of locale theory as the constructive (choice-free) counterpart of topology. The main ``new'' result (actually the localic translation of a result established for spaces by the same author over twenty years ago) is that compactifications of a given locale L correspond bijectively to certain binary ``strong inclusion'' relations on (the frame corresponding to) L. The author also shows that a locale has a smallest compactification iff it is locally compact and regular, iff it is isomorphic to an open sublocale of a compact regular locale.