To defragment is to use software to reorganise data on a hard disk drive (HDD) by bringing together fragmented pieces of files that have been scattered across the disk over time. When files are saved, they can be split into multiple segments, which may slow down access and performance. Defragmenting "tidies up" the drive, improving read and write speeds, enhancing overall system efficiency, and sometimes freeing up usable space. While less relevant for modern solid-state drives (SSDs), defragmentation remains important for maintaining optimal performance on traditional hard drives used for storing large image files and archives.