This is all out about harddisk how it's defragmentation

1. By-Rohit Parihar
& Guided by :-
Jignesh Kikani Jatin M.Patel

2. Fragmentation happens to a volume over time
as you save, change, or delete files. The
changes that you save to a file are often
stored in a different place on the volume than
the original file.
Fragmentation makes your hard disk do extra
work that can slow down your computer.
Removable storage devices such as USB flash
drives can also become fragmented.

3.  Disk Defragmenter rearranges
fragmented data so your disks
and drives can work more
efficiently. Disk Defragmenter
runs on a schedule, but you can
also analyze and defragment your
disks and drives manually.

5. A B C D FREE SPACE
50MB 80MB 60MB 70MB
A
50MB 80MB 60MB 70MB
B D FREE SPACE
INSTALLING NEW SOFTWARE (F) WHICH CONTAIN 90MB
50MB 80MB 60MB 70MB 30MB
A B F D F
FREE
SPACE
So F becomes fragment files
50MB 80MB 90MB 70MB
A B F D
FREE
SPACE
uninstalled
the C S/W

10. Estimated disk usage after defragmentation
Comparing Both Before & After fragmentation

13.  To use the defrag tool, just
enter defrag followed by the parameters you
want to use. As usual, you can view the
command’s help file by entering defrag /?. Then
to use defrag, just enter the following, like you
would with many command apps.
 Syntax :-
defrag [name of your drive]
[parameter] [extra parameters]