Defragmentation is the maintenance process used on mechanical hard disk drives (HDDs) to physically reorganize stored files. With constant use, the data from a single file ends up being written in pieces scattered across different sectors of the disk, a phenomenon known as fragmentation. This forces the drive's read head to make excessive movements to read the complete file, which makes data access slower.

The defragmentation process rewrites these data blocks contiguously, that is, in a continuous and uninterrupted sequence, in addition to consolidating the available free space. In the context of audio production, keeping a hard drive defragmented is essential to ensure the transfer speed needed to record and play back multiple tracks simultaneously without overload errors. It is important to note that this process is specific to mechanical disks and should not be performed on solid-state drives (SSDs), as it can reduce their lifespan without providing performance benefits.