Changes

Because file systems are typically used on block-oriented devices (like hard disks), they are optimized for use on such.  One such optimization is the ability to store files in discontiguous segments, called '''extents''', which is both faster for resizing files, and makes efficient use of the fixed space on such devices.  Over time, these file extents become scattered across the device, which can result in slower file access (and may significantly slow the operating system as well) due to the seek and latency times inherent in mechanical devices.  The use of defragmenting software was necessary to collect the extents together and make the file system operate faster.  Most modern systems use other methods to keep the file systems defragmented, and modern storage devices (such as SSDs, which do not possess mechanical access mechanisms) are less subject to slowness due to fragmentation.

Because file systems are typically used on block-oriented devices (like hard disks), they are optimized for use on such.  One such optimization is the ability to store files in discontiguous segments, called '''extents''', which is both faster for resizing files, and makes efficient use of the fixed space on such devices.  Over time, these file extents become scattered across the device, which can result in slower file access (and may significantly slow the operating system as well) due to the seek and latency times inherent in mechanical devices.  The use of defragmenting software was necessary to collect the extents together and make the file system operate faster.  Most modern systems use other methods to keep the file systems defragmented, and modern storage devices (such as SSDs, which do not possess mechanical access mechanisms) are less subject to slowness due to fragmentation.