macOS High Sierra introduced Apple File System, abbreviated APFS, as the Mac’s new default file system. High Sierra was released as macOS 10.13 in 2017, beginning Apple’s transition away from the older HFS Plus format.
APFS was designed for modern Apple hardware, especially solid-state and flash storage. It includes features such as snapshots, space sharing between volumes, strong encryption support, and copy-on-write behavior. These capabilities can make operations such as duplicating files more efficient because the system does not immediately need to copy every block of data.
A common mix-up is confusing APFS with HFS+. HFS+ was the long-standing Mac file system before High Sierra, while NTFS is primarily associated with Windows and exFAT is a cross-platform removable-storage format. High Sierra’s APFS conversion applied primarily to compatible startup drives; some Fusion Drives and other configurations received support later through updates. APFS remains a key foundation of current Apple operating systems.