A good defragger not only places files contiguously, but places OFT-used files nearer the outer-edge of the hard-disk, and system-files closer to the hub. This reduces "latency", -the time it takes the swing-arm to move between files. The shortest distance between any two points being a straight line (or in the case of defragged-optimized in this case), releatively straight line.

Often, a so-optimized/defragged HDD is 100-300% faster (we're talking scores of milliseconds here, so in real time, -a few scant seconds are shaved from load-times...)

The more full your hard drive, the more important it is to defrag. The more files you add and delete from your computer, the more important it is to defrag. You shouldn't let your hard drive become more than 4% fragmented and certainly not more than 10%.

Defragging my hard drive does seem to make files load faster for a while. It is not top on my computer list of things to do. It is said you should do it once a month. I start it before I go to bed since it can take several hours to do.

Defragging is never something that must be done... but it is something that will be noticible for your overall computing speeds.  Every time your computer needs to look for a file, it is just a slight bit faster to load a unfragmented file than it is for a fragmented one.  That builds up over time like muk.  Defrag when ever you think of it before bed.  Then you will never have to worry about your computer needing it.  (the key here would be to defrag once every week to month or two'ish)

Often is not often enough. Do it as much as you can (esspecially if you manage large amounts of data). On the other hand don't become obsessive about it, the performance difference is noticable at best.

Defragging your hard drive can certainly make your computer run more efficiently and thusly faster. Your computer writes to your hard drive in blocks. Each block can hold a specific amount of data. If the data being written to the drive is larger than one block, the data may span several blocks. The problem comes in when a portion of the data being written spans more than one block, with the last block not being completely full of data. The computer marks that last block as used, even though that block isn’t really full of data. So, after time you end up with a hard drive with lots of usable but unavailable data storage space. Over time this can also cause your computer to run slower since the hard drive is having to work harder to retrieve data. The defragged hard drive will improve the performance of the computer and in reality, reduce wear and tear on the hard drive itself. In essence, the defrag utility, frees up the empty unused space on these blocks that were previously marked as used. Then it lines all the data up in neat little rows. This makes the access time quicker and may even extend the life of the hard drive. Defragging should take place on a regular basis to keep your computer running efficiently. I recommend setting it to run on its own once a month and to do so in the wee hours of the morning or whenever you know you won’t be using your computer for a couple of hours. If you don’t want to set it as a scheduled task and prefer to run the defrag manually, it should be run when your drive is 4%-5% fragmented. Once a drive gets to 10% fragmentation or more, the computers speed will start to become noticeably slower.

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There is no hard rule regarding the frequency of defragmentation. That depends on how often you use your computer. If you notice that your computer is slower than usual (e.g. it will take more time to boot or open an application) then it is time to defragment. A third party defragmentation software like Auslogics defragments faster than the integrated windows defragmentation utility.

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There is indeed no hard-rule to when you should defrag your computer. As of my personal experience I rarely defrag my computer but it is as fast as lightning. Defrag your computer if you experience it's running a lot slower than usual. I suggest you don't use the build-in Microsoft defragmenter as I think it is total rubbish. You're better off with something like Smart Defrag 2 from Pirisoft or some other third-party defragmenter, that's what I use and it automatically defrags my computer.

Yes, if you see it is running slow or if you know you've been adding lots of files or get error messages, defrag! It saves you time and expense in the long run.

It is important to note that SSD (Solid-state drive) do not need defragging. So if your computer posseses a SSD it will automatically disable the defragging option on that drive.

It is true that defragmenting a computer hard disk drive could significantly boost the entire performance of the computer system. However, this should be done once in every 2 months to be safe. Sometimes once a month or week could also be suitable depending on the the fragmented files from your hard disk drive.

If you are using Windows OS, you can use the preinstalled defragmenting software of it and use it to analyze your hard disk for possible fragmented files.

Sometimes they do - how often depends on how you use them - de-fragging puts your data in order so it is easy for the computer to find information. If you find your computer slowing down running de-frag might help - part of the utility will quickly check and see if it is needed,

Yes it does. Defragging is a process done to a hard disk in order to improve performance and recover some lost disk space. Defragging is an essential part of a PC's upkeep as it keeps all the data on your hard disk in an easily readable order. If a hard disk is left without defragging, then over time the disk will begin to lose performance and also slowly reduce the available capacity to data.