How Defragmenting Works

When a program saves a file on a disk, it puts the file into an empty space on the disk. When it saves changes to the file, it saves the changes to another empty space on the disk. Each time it saves the file, it puts information about it into whatever large empty space on the disk it can find. Because the different pieces of the file are separated -- or fragmented -- opening and reading the file can get slower and slower.

The solution is to defragment the disk. Disk defragmentation takes all the pieces of each file, and stores them in one place. It also makes sure programs are each in one place, and that unused space on the hard disk is all together.

Defragmenting a disk is like sorting and arranging items in a storage room; boxes holding similar things are combined, and all the boxes in the room are stacked neatly to create more space. Defragmenting does not change any of the files' contents, and does not affect anything you see on the screen (documents, shortcuts on the desktop, etc.)

If you'd like to learn how to defragment manually, click here.