is the area in a region or a page that is not used by the job occupying that region or page. This space is unavailable for use by the system until that job is finished and the page or region is released Absolute code Logical address Internal fragmentation is unused space between allocated regions of memory. Typically this results in memory regions that are too small to. satisfy a memory request Input queue it is typically generated by the CPU. Physical address it is typically seen by the memory unit, that is, the one loaded into memory. External fragmentation