HFS Plus or
HFS+ is a
file system developed by
Apple Inc. It serves as the primary file system of
OS X. HFS+ was developed to replace the
Hierarchical File System (HFS) as the primary file system used in
Macintosh computers (or other systems running
Mac OS). It is also one of the formats used by the
iPod digital music player. HFS Plus is also referred to as
Mac OS Extended (or, erroneously, "HFS Extended"), where its predecessor, HFS, is also referred to as
Mac OS Standard (or, erroneously, as "HFS Standard"). During development, Apple referred to this file system with the codename
Sequoia.