Disk Defragmenter window

Disk Defragmenter is split into two main areas. The upper portion lists the volumes on the local computer. The lower portion displays a graphic representation of how fragmented the volume is. The colors of the display indicate the condition of the volume:

Red areas show fragmented files.
Blue areas show contiguous (nonfragmented) files.
White areas show free space on the volume.
Green areas show system files, which cannot be moved by Disk Defragmenter. These system files are not part of the Windows operating system but belong instead to the NTFS file system. The green areas appear only on NTFS-formatted volumes.

By comparing the Analysis Display band to the Defragmentation Display band, you can see the improvement in your volume after defragmenting it.