Clones allow the operating system to make efficient file copies on the same volume without occupying additional storage space. Changes to a cloned file are saved as [[Delta encoding|delta extents]], reducing storage space required for document revisions and copies.<ref name="digging-into-apfs"/> There is, however, no interface to mark two copies of the same file as clones of the other, or for other types of [[data deduplication]].
The feature is automatically available when youa copyuser copies any files using the [[Finder (software)|Finder]] application, which is [[macOS]]'s default [[file manager]], but not when using the <code>[[cp (Unix)|cp]]</code> command.<ref>{{cite web|title=A ZFS developer's analysis of the good and bad in Apple's new APFS file system|website=Ars Technica|date=2016-06-26|url=https://arstechnica.com/gadgets/2016/06/a-zfs-developers-analysis-of-the-good-and-bad-in-apples-new-apfs-file-system/|ref={{sfnref|Ars Technica|2016}}|access-date=2025-02-17|quote="Side note: Finder copy creates space-efficient clones, but cp from the command line does not."}}</ref> To do that on the [[command-line]], the <code>cp</code> utility on macOS has a <code>-c</code> parameter that allows it to use the <code>clonefile</code> [[system call]].<ref>{{cite web|title=[dedup] Use APFS clone (CoW) on macOS · Issue #219 · pkolaczk/fclones|website=GitHub|date=2023-08-10|url=https://github.com/pkolaczk/fclones/issues/219|access-date=2025-02-17}}</ref>
