When a computer starts writing to hard drive, it write everything in a spiral fashion. A healthy spiral would look like this:
But as time passes, you’re bond to delete some file off of the hard drive, that will leave an empty space in the spiral. And now it looks like this:
When the computer starts writing on the hard drive again, the writing process will start in the first empty space that the computer finds. In the case of our last spiral image, that first empty space will be the one previously reserved to the deleted files, witch as you can see is a limited space. If the file being written is larger then the available space, the computer will continue writing on the next empty space that it finds, that’s called fragmentation:
With time, the fragmentation process will slow down the computer, because loading files will take more time since the computer has to search the hard drive for all the different pieces of the file
Defragmentation will reverse the fragmentation process by finding all the pieces of a file through the spiral, lining them together in an orderly fashion, thus making it eithier for computers to find the files requested. Once defragmented, the spiral will look healthy again.
