Defragmenting your hard drive Your hard drive becomes fragmented when your operating system breaks a file into smaller pieces because there isn't enough room in one contiguous section on the hard drive. This occurs more commonly when a file is created and then modified at a later date. The operating system keeps track of where all the parts of the file are saved. When you re-open the file, the operating system must find all the pieces and re-assemble them. The more fragmented files you have on your hard drive, the slower the computer's performance.
Defragmenting your hard drive rearranges the files so each file can be stored as a single unit or in consecutive areas. The Windows operating system provides a disk defragmentation program.
To defragment your hard drive, select the version of Windows you're using: