This is a work in progress - this first post will be edited a loooot in the coming hours. Briefly discuss what fragmentation is Think of files on your drive, as one big long string of words on pages. If those words were out of order (words if those order of out were), you can still get them right if you know where to find them and put them back in order/make sense of them, but it takes longer. Now imagine if the LETTERS were out of order too. Defragmenting is simply putting them back in order - but there are many ways of doing so. Below is a list of various methods that don't just defragment - they relocate the files for better performance, too. Describe various methods of HDD Defragmentation Fragmented files only This is making sure each file is in one piece. Instead of the words out of order analogy above, think of this as making sure the letters in each word are in the right order. Each word in a sentence may be in very different locations, but at least the words are in one piece. This is what most quick defraggers (and operating systems) use By name/Alphabetical order Simple really - this doesnt just defrag, it sorts the files too. ALl the files in C:\windows are physically near each other, so its quicker to load lots of them at once - less time is wasted moving between them (think all your pages are stapled together in order in a book, not just numbered in a random pile) Recently used an odd one, for servers only really. This method puts files most recently used at the start of your drive/partition (fastest area), and your least used ones at the back. This may work well in some situations, but it has two downsides: if your patterns of usage change, a defrag will have to move every file to its new location, taking a long time to defrag. I recommend this only for drives where the contents don't change often. High/Low performance mode (Ultimate defrag only) Labelled "performance" and "archive" in Ultimate defrag, its got a mode where you can choose files to go at the start of the drive (performance) and files to go at the back (archive) with everything else fitting in the middle. My MP3 collection doesnt need to load fast, but my 300GB of games does: (for reference, i use folder/file name (aka alphabetical order) + manually selecting low/high performance folders) purple is my games/steam folders, blue is random crap, green is my MP3's and installers/game patches. For those who dont know, the outer edges of a disk are faster than the inner edges - therefore, my games are now loading faster than my MP3's. *background/scheduled/idle defraggers Guide for how to set up ultimate defrag to defrag your files properly Select the drive you want to defrag at the top. hit the big yellow options button tick custom on high performance and archive, and pick the folders you want. Kinda obvious what i want sped up on my games partition. Follow the same procedure for your 'archive' folders. Select the method you want, hit the small blue 'options' button - set it as following. hit start and go... the more often you do it, the quicker subsequent times will take. If you dont change the files on the drive much, defrags will be very quick. discuss how often one should defrag This varies so much. i went 6 months without defragging and didnt even notice any slowdown, except on boot times. Once OS had booted, i didnt notice anything. Thats because in my case, only my C: drive fragments, and i keep very little on there. Discuss methods to reduce fragmentation Partition! your OS will fragment constantly, your games drives only when you install/delete stuff, and storage drives generally wont fragment ever.