Fragmentation makes your hard disk do extra work that can slow down your computer. Disk Defragmenter rearranges fragmented data so your hard disk can work more efficiently. Disk Defragmenter runs on a schedule, but you can also defragment your hard disk manually.
Open Disk Defragmenter by clicking the Start button , clicking All Programs, clicking Accessories, clicking System Tools, and then clicking Disk Defragmenter.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Click Defragment Now.
Disk Defragmenter might take from several minutes to a few hours to finish, depending on the size and degree of fragmentation of your hard disk. You can still use your computer during the defragmentation process.
Advanced users can use the command line tool Defrag.exe to generate detailed reports and perform other advanced tasks. For more in-depth information, go to the Microsoft website for IT professionals.