Difference between internal and external fragmentation is a topic of interest to many who like to improve their computer knowledge. Before knowing this difference, we have to see what fragmentation is. Fragmentation is a phenomenon that occurs in computer memory such as Random Access Memory (RAM) or hard disks, which causes wastage and inefficient usage of free space. While the efficient usage of available space is hindered, this causes performance issues, as well. Internal fragmentation occurs when memory allocation is based on fixed-size partitions where after a small size application is assigned to a slot the remaining free space of that slot is wasted. External fragmentation occurs when memory is dynamically allocated where after loading and unloading of several slots here and there the free space is being distributed rather than being contiguous.