Abbreviation for Hierarchical File System as is used by the Macintosh computer system for hard disk data organization. HFS has been used by the Macintosh since about 1986 and is still in widespread use today. Recently Apple has introduced an updated architecture they are calling HFS+. HFS+ addresses a variety of shortcomings in the old HFS, including the ability to handle files over 2 gig in size, allowing names up to 255 characters long, using more of the available hard disk space and packing the data more tightly on the drive, thus conserving space.