What is the difragmentation?

'Defragmentation', or 'Defrag' is a word used in computer systems, and it means the process of scanning the file system and rejoining any split files back into consecutive pieces.

Defragmentation is the process of putting all of a file into the same sector.

This allows the file to be acccessed without having to move the head (which is a slowing action).

Without defragmentation a file could be split up all over the hard drive platter forcing the head to move here and there to collect all the data.

Because some programs write data that can never be moved, yo should always use your defrag program before installing any new software, for faster program access in the future.

In the context of administering computer systems, defragmentation is a process that reduces the amount of fragmentation in file systems. It does this by physically reorganizing the contents of the disk to store the pieces of each file close together and contiguously. It also attempts to create larger regions of free space using compaction to impede the return of fragmentation. Some defragmenters also try to keep smaller files within a single directory together, as they are often accessed in sequence.

http://en.wikipedia.org/wiki/Defragmentation

It is taking all the computer info and stacks it altogether thus helping the performance of the computer. Should do it once every 28 days.

I really simple way of putting it is:
A really big library that has lots of levels in it, and someone has run though it and put a bunch of the books in the wrong order
so now I'll send in this robot which will move from point a-z,level 1-100 and everything is now back in order
I told this to a little old lady not to long ago, because I just could not explain defrag to her but the story made since to her and she was happy LOL