The Windows 7 defragmenter is a program within the operating system that rearranges and sorts data on hard drives and USB flash drives. This makes storage devices perform more efficiently.
It takes time for the head of the disk to travel from one side to the other. If similar files are far apart, the time it takes for the disk head to read everything increases. Defragmenting a hard drive with a defragmenter alleviates this issue. Hard drives with more than 10 percent fragmentation should run the defragmenter program. On Windows 7 operating systems, the defragmenter is typically set to a timer, and many users choose to have the program run on a schedule.