Essentially, it is the fact that when a file is saved on the hard drive, it will often get split into two or more sections, and stored in two or more physical locations on the disk. What this means is that when there is a request for the file, the hard drive must gather it up again from two or more locations. There is a slight performance loss, when this happens.
Defragging attempts to gather all the fragments into single locations, and speed up file access.
Windows disk defragmenter is a standard windows utility.
NOTE: Windows 7 and greater does defragmenting automatically.
Click: Start -> All Programs -> Accessories -> System tools -> Disk Deframenter
For each drive ...
NOTE: This can take some time [ie., many minutes] to complete
I have written an MS Visual Basic Script which you can get here: DMHD.vbs It will clean and defrag multiple hard-drives on Windows®. Right click and save as 'DMHD.vbs'. Double click file to launch.
NOTE:Your antivirus and antispyware programs will 'sound an alarm' when you try and run this script. This is normal, as many malicious programs use scripts too. All we can do is make the code available, and leave it to your discretion. Mcafee SiteAdvisor Gives us a 'Safe' rating.