004 file extension used by various data archiving tools. The data archiving process allows users to create backups of important data in a compact, compressed form to reduce disk space usage.

004 file is the fourth part of multi-volume data archive. Multi-volume archives are used for dividing large data into smaller-sized parts. Such procedure allows fitting data on multiple storage devices of smaller size, such as CDs or DVDs. In order to unpack such archive, all its parts must be placed in the same file folder.