What does “Defrag” do anyway?

By Sandra Clitter  

OK…so you know that you’re supposed to “defrag” your computer, but most people don’t know why they’re doing it, or what it’s supposed to accomplish. Others don’t know where/how to do it. Here’s a quick lesson.

“Defragging” your computer is short for ‘defragmenting’. Computer hard drives get disorganized as information is added and deleted. While a computer is ‘smart’ enough to be able to locate/assemble this ‘disorganized’ information, it can operate faster if the information is stored ‘neatly’. How exactly, does information get ‘disorganized’ on a computer?

I like to use the analogy of a filing cabinet. If you are filing papers in a filing cabinet, you can store information in various drawers, and within the drawers, in various folders. Inside the folders, you can store information oldest to newest, newest to oldest, or haphazardly. If you’re in a hurry, you might misfile a paper. Perhaps you put it in the wrong place in the file. Maybe you put it in the wrong folder. Worse, you put it in the wrong drawer, altogether. Finding that misplaced piece of paper takes longer and longer the more misplaced you filed it. I’m not telling you anything you don’t know…its common sense.

Now, let’s think of your computer. Your computer ‘files’ documents (electronic files) as you work on them and save them. Every time you ‘file’ your electronic document, your computer looks for the first available space to stick the piece of paper. You’re computer doesn’t work alphabetically…it works on the first available space. If only part of the file fits into the space, then it actually rips the file apart and stores some parts of the file in one place, and some in another. Then, your computer writes a separate ‘note’ to itself telling itself all the places it filed that document. Don’t worry…your computer is good at this tracking. Unfortunately, the more files it gets, stored in more places, the longer it takes to locate the various pieces of the file and present them to you.

So…what is “Defrag”? “Defragging” your computer means that you’re going to reorganize all the files on your computer, so that they are stored logically. When you defrag your computer, you tell your computer to go reorganize itself! You tell it to go through all the files, gather them together in a logical fashion (rather than the ‘haphazard’ way they are stored when you first save them), then store them in the the most accessible (for a computer) manner.

Once your computer is defragged, it will be able to locate/access files faster. The more defragmented the hard-drive (think disorganized), the longer it takes to access the files.

Windows computers all have a built-in defragmentation tool. To locate it go to Start-Programs-Accessories-System Tools, then finally, select ‘Disk Defragmenter’. Differing versions of Windows have different Defragmenters, so I won’t show screen shots because your version might look different than mine. Once you open up the program, select a drive to be defragmented (typically ‘C’), then ‘Defragment Selected Volume’, and ‘Start’. This utility is basic, but functional.

If you want a Defragmentation Tool that is a bit more sophisticated (e.g. one which will automatically defrag, but is smart enough to know when you’re working on your machine, so it shouldn’t try to defrag), try Smart Defrag. It’s a FREE tool, easy to download and install, but offering some features that the basic Windows Defragmentation Utility doesn’t offer, click here for Smart Defrag Download.

Warning: If you’ve never ‘defragged’, this process can take quite a while. I recommend starting it at night, and letting it run while you sleep! It should be done by morning!


  1. Posted June 2, 2013 at 7:33 pm | Permalink | Reply

    i use a progam called Auslogics Dick Defrag and it’s a really good progam to use to. I Highly recomend it.

  2. Posted April 7, 2011 at 8:52 am | Permalink | Reply

    Thanks Sandy! I went through your steps and was pleasantly surprised to find that I automatically “defragment” on a weekly basis. I didn’t even know what it was or that I was supposed to be doing it! Thanks for all your great tips!

  3. lac
    Posted April 7, 2011 at 8:04 am | Permalink | Reply

    Nice article on defrag Sandra. I think its the most underutilized utility and many users dont defrag until the pc has really slowed down. If performed proactively defragging does benefit the HDD and overall performance of the systems by keeping data access fast and smooth. Its also true that the more regularly its run, the lesser it takes to complete each time. For those who dont want to defrag manually or for large IT environments there are very efficient real time auto defraggers that do a splendid job of tackling fragmentation with absolutely no manual assistance.

    • Posted April 7, 2011 at 9:22 am | Permalink | Reply

      Glad you enjoyed it, and YES, the auto-defrag settings are great…you don’t even need to think about it then.

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