defragmentation

Defragmentation is the process of reorganizing data on a computer's hard drive so that related pieces are stored together rather than scattered across the disk.

Over time, files become fragmented—split into chunks stored in different locations—which slows retrieval.

Defragmentation consolidates these fragments, improving performance.

The term applies mainly to older spinning hard drives; solid-state drives don't benefit from it.

Often shortened to defrag: I need to defrag my hard drive.