An information storage medium, and a recording/reproducing apparatus and method, the information storage medium including a plurality of recording layers, each layer including a lead-in area or a lead-out area, a data area, a middle area, and a dedicated area, wherein the data area is flexibly allocated according to data capacity to be recorded in each of the recording layers, the middle area is allocated behind the data area, and the dedicated area is allocated behind the middle area. The dedicated area for a special purpose may selectively be allocated in an outer circumferential area of the information storage medium, i.e., an optical disk including a plurality of recording layers. In particular, optical disks in various formats are provided in which dedicated areas for special purposes can selectively be allocated in outer circumferential areas of the optical disks depending on recording characteristics of the optical disks and the outer circumferential areas.