ɐn ˌoʊvɚlˈeɪ mˈænɪdʒɚ, ˈiːðɚ pˈɑːɹt ʌvðɪ ˈɑːpɚɹˌeɪɾɪŋ sˈɪstəm ɔːɹ pˈɑːɹt ʌvðɪ ˌoʊvɚlˈeɪ pɹˈoʊɡɹæm, lˈoʊdz ðə ɹᵻkwˈaɪɚd ˌoʊvɚlˈeɪ fɹʌm ɛkstˈɜːnəl mˈɛmɚɹi ˌɪntʊ ɪts dˌɛstɪnˈeɪʃən ɹˈiːdʒən wɛn ɪɾ ɪz nˈiːdᵻd; ðɪs mˈeɪ biː ˌɔːɾəmˈæɾɪk ɔːɹ vˈaɪəɹ ɛksplˈɪsɪt kˈoʊd.
An overlay manager, either part of the operating system or part of the overlay program, loads the required overlay from external memory into its destination region when it is needed; this may be automatic or via explicit code.