What is disk defragmentation?

Disk defragmentation is the process of consolidating fragmented data on a volume (such as a hard disk or a storage device) so it will work more efficiently.

Fragmentation happens to a volume over time as you save, change, or delete files. The changes that you save to a file are often stored in a different place on the volume than the original file. This doesn't change where the file appears in Windows—only where the bits of information that make up the file are stored on the actual volume. Over time, both the file and the volume itself become fragmented, and your computer slows down as it has to look in different places to open a single file.

Disk Defragmenter is a tool that rearranges the data on your volume and reunites fragmented data so your computer can run more efficiently. In this version of Windows, Disk Defragmenter runs on a schedule so you don't have to remember to run it, although you can still run it manually or change the schedule it uses.

For more information, see Improve performance by defragmenting your hard disk and Schedule Disk Defragmenter to run regularly.