What is Defragmentation?

Hi all I have vista home edition installed on my PC. I don't know much about computer terms. I have heard lot about Defragmentation that it is necessary . can anybody explain me what it is?

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 organizing 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.

Fragmentation occurs when the operating system cannot or will not allocate enough contiguous space to store a complete file as a unit, but instead puts parts of it in gaps between other files (usually those gaps exist because they formerly held a file that the operating system has subsequently deleted or because the operating system allocated excess space for the file in the first place). Larger files and greater numbers of files also contribute to fragmentation and consequent performance loss. Defragmentation attempts to alleviate these problems.

Disk defragmenting is an essential maintenance operation. Vista runs completely automated.

However, it may be practical, before a video editing or external disk repartitioning, to manually trigger a disk defragmentation.

This tip explains how to add an entry "Defragment" in the menu that appears when you click the right button on a disk Windows Explorer.

• Open the Start menu in Windows Vista (just by pressing the [Windows])
  
  
• Enter regedit in the search field and click OK by [Enter]
  
  
• Deploy the tree HKEY_CLASSES_ROOT \ Drive \ shell
  
  
• Go to the Edit menu and then New Key
  
  
• Enter the name runas
  
  
• Then double click "(default)" and enter "Defragment"
  
  
• Go to the Edit menu and then New Key
  
  
• Enter the name Command
  
  
• Then double click "(default)" and enter "defrag% 1-v"
  
  
• Close Regedit
  
  
• Open Computer in the Start menu, click the right button on a disc and make sure the item appears Defragment!
  

many many thanks for such awesome replies and tips....:notworthy ...

Defragmentation is the opposite of fragmentation.

When a file is written to the hard drive, it may get split up into fragments, resulting in "fragmentation". Reading a fragmented file takes longer and gives poor performance.

When you "defragment", the file fragments are collected and rearranged contiguously to improve read performance. Often the files themselves are rearranged/relocated to different sections of the platter to improve performance.

There is an informative presentation on defragmentation at the Diskeeper Website.
http://www.diskeeper.com/diskeeper/tour/index.html

FYI: These guys developed the first defragmenter for Windows and are synonymous with defragging. For eg, the XP defragger is a stripped down version of an ancient Diskeeper edition.