Disk Defragmenter locates fragmented files and folders on local volumes. A fragmented file or folder is split up into many pieces and scattered over a volume.
When a volume contains a lot of fragmented files and folders, Windows takes longer to gain access to them because it requires several additional disk drive reads to collect the various pieces. Creating new files and folders also takes longer because the free space available on the volume is scattered. Windows must then save new files and folders to various locations on the volume.
Disk Defragmenter moves the pieces of each file or folder to one location on the volume, so that each occupies a single, contiguous space on the disk drive. As a result, your system can gain access to your files and folders and save new ones more efficiently. By consolidating your files and folders, Disk Defragmenter also consolidates your free space, making it less likely that new files will be fragmented.
The process of finding and consolidating fragmented files and folders is called defragmentation. The amount of time that defragmentation takes depends on several factors, including the size of the volume, the number of files on the volume, the amount of fragmentation, and the available local system resources. You can find all of the fragmented files and folders before defragmenting them by analyzing the volume first. You can see how many fragmented files and folders are saved on the volume and then decide whether or not you would benefit from defragmenting the volume.
Disk Defragmenter can defragment FAT, FAT32, and NTFS formatted volumes.