ɐ mˈaɪkɹəsˌɑːft ɹɪzˈɜːvd pɑːɹtˈɪʃən ˌɛmˌɛsˈɑːɹ ɪz ɐ pɑːɹtˈɪʃən əvə dˈeɪɾə stˈoːɹɪdʒ dɪvˈaɪs, wˌɪtʃ ɪz kɹiːˈeɪɾᵻd tə ɹɪzˈɜːv ɐ pˈoːɹʃən ʌv dˈɪsk spˈeɪs fɔːɹ pˈɑːsᵻbəl sˈʌbsᵻkwənt jˈuːs baɪ ɐ wˈɪndoʊz ˈɑːpɚɹˌeɪɾɪŋ sˈɪstəm ɪnstˈɔːld ˌɔn ɐ sˈɛpɹət pɑːɹtˈɪʃən.
A Microsoft Reserved Partition (MSR) is a partition of a data storage device, which is created to reserve a portion of disk space for possible subsequent use by a Windows operating system installed on a separate partition.