Whenever you move or copy a file, delete an email, download or uninstall a program, you change the location in which related information is stored in your system. Over time, several blocks of data related to a specific file can be stored in multiple places on your hard disk, where ever there is space available.
When data gets fragmented in this manner, it increases your hard drive’s data access time, burdening your hard disk and significantly slowing down your computer. It may even cause physical damage to your system as your hard drive’s read/write head is forced to work extra hard searching for data all over the hard disk.
Vista’s Disk Defragmenter utility scans your system to locate all of the non-contiguous data and file fragments. It then re-arranges and consolidates them on the hard disk. This system tool can free up potentially huge amounts of hard disk space, increase disk access performance and enable the hard disk to run more efficiently.