As files of different sizes are added to your hard drive, they are placed into line with other files. If a file is larger than the available space between two existing blocks, it’s split up and fragments of the files are stored in different spots on your hard drive. As your system is always creating and deleting files, over time, lots of files are stored in fragments – a bit of the file here, then another bit in this open space over there, and so on. When you access these files, the hard drive has to jump from spot to spot to reassemble all of the fragments.

A hard drive can access the files near the center of the head faster than it can the outside of the head. Unfortunately, files which are frequently accessed are not always stored at the front of the drive as would be desired.

Defragmenting your hard drive solves these problems. Its primary purpose is to reassemble those pieces of files into one contiguous section. In older versions of Windows, you had to manually defragment your hard drive (most people never did), but with Windows 7, it’s scheduled to happen automatically. You may find a need to manually defragment your hard drive, and if so, here’s how you do it:

1. Click on the Start menu and select Computer.
2. Right-click on your C: drive and select Properties.
   
3. Click on the Tools tab.
4. Click Defragment now…
   
5. The defragmenter is scheduled on this computer to run every Wednesday at 1:00 AM. Currently, neither hard drive is fragmented – you can see that as it is 0% fragmented.
6. To defragment a hard drive, click once on it then click Defragment disk.
7. Analyzing the disk will determine the amount of defragmentation required. Click on Analyze disk to analyze it.
   
8. After analyzing the drive, it found that the drive is 7% fragmented.
9. To defragment the hard drive, click Defragment disk.