There is a little utility that comes with every version of Microsoft Windows; it’s called Disk Defragmenter. It’s under the Accessories folder, under System Tools. This handy little utility program can keep your hard drive running quickly, which is something that is pretty important to Windows users, because Windows uses all kinds of temporary files to run, which means it is almost constantly using your hard drive; so if your hard drive slows down, your whole computer will slow down.
The reason this utility exists is because something needs to be done to rearrange how your files are stored on your hard drive; and this is because of the way that your operating systems stores file.
What happens is, when you create a file, of any type, a marker is created on the hard drive to mark the beginning of the file and then to point to the next part of the file since files are actually little blocks of data linked together. Thus, you wind up with an initial block which points to next block, which itself points to the next block after that until you get to the end of the file. Think of it like this: beginning block–>next part–>next part–>next part–>end. Which is all fine and well, except for when those blocks that are pointed to don’t sit physically next to one another on your hard drive, but instead are located somewhere else which makes your hard drive have to go find them; it’s this going and finding the next part that takes up some extra time.
Files have their parts separated when they grow. For example say you start a Word document then close it down. You might have four contiguous blocks of data. Then, say you start an Excel spreadsheet and then save it and close it. Then, you go open that first Word document again and add something to it, then save and close it. Your hard drive date would look like this: First Word part–>next Word part–>next Word part–>next Word part–>next Word part–>First Excel part–>next Excel part–> next Excel part–> next Excel part–>End Excel doc–>Next Word part–>next Word part–>End Word doc. Clearly this is messy and will get messier as time passes.
The defragmenter utility fixes this by moving stuff around on your hard drive so that all of the parts of each file are right next to one another so that your hard drive doesn’t have to go searching for the other parts of your document ever time it needs to read something, which again, becomes important when you consider that Windows reads and writes to files pretty much anytime it does anything, thus, having your hard drive move as quickly as its capable of doing will keep your computer running as quickly as it is capable of as well.