Filesystem
Filesystems are Electronic Formats that are a prerequisite to being able to read any file off a digital medium — you have to be able to mount the filesystem, and thus read it, in order to be able to read a file.
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Single-system filesystems
(How files are organized on one system or device, such as a disk, tape, or flash memory; see next category for networked and cloud filesystems. Of course, any filesystem can be made available on a network to remote devices, but these are the native filesystems present on the storage device itself.)
- Acer Fast Filesystem (SCO OpenServer)
 - ADFS (Acorn MOS, RISC OS)
 - AdvFS(Advanced File System, Digital/Tru64 Unix)
 - Ami File Safe (Amiga)
 - APF Imagination Machine disk file system
 - Apple DOS file system (Apple II; see also ProDOS below)
 - Atari File Management Subsystem (FMS: Atari 400/800)
 - AthFS (AtheOS/Syllable)
 - BFS (BeOS)
 - btrfs (Linux)
 - CBMFS (Commodore 64, PET, etc.)
 - Compucolor file system
 - CP/M file system
 - DDFS (Data Domain File System)
 - DTFS (Desktop File System, SCO OpenServer)
 - EFS (Extent File System, SGI IRIX. Replaced by XFS)
 - EOS file system (Coleco Adam "data pack" tape drives and disks)
 - exFAT (Microsoft, for flash memory)
 - ext (developed for Linux, previously used MINIX fs)
 - ext2, ext3, ext4 (these are all just variants of each other)
 - F2FS, (Flash Friendly Filesystem)
 - FAT8
 - FAT12
 - FAT16
 - FAT32
 - FFS (Amiga Fast File System)
 - Files-11 (VMS)
 - Fossil (Plan 9)
 - fuse-exFAT (open-source clone of exFAT)
 - HAMMER (DragonflyBSD)
 - HFS
 - HFS+
 - HPFS (OS/2 native file system)
 - ISO 9660
 - JFFS2
 - LanyFS (Lanyard Filesystem)
 - LogFS
 - MDR (audio instrument format close to MSDOS)
 - MFS (ancient Macintosh filesystem)
 - MINIX file system
 - NILFS2
 - NTFS
 - POHMELFS (distributed Linux filesystem)
 - PRAMFS (Persistent & Protected RAM File-System)
 - ProDOS file system (Apple)
 - QFS
 - ReFS (Microsoft's new FS- Resilient Filesystem, on Windows 8 Server)
 - ReiserFS
 - SDFS (Deduplication based filesystem)
 - SkyFS (SkyOS)
 - SMB (Server Message Block, a protocol for a networked filesystem)
 - SOS file system (Apple III)
 - squashfs
 - UCSD p-System Filesystem (UCSD Pascal)
 - UDF
 - UFS (Unix Files System, Solaris and BSD)
 - VMUFAT (Filesystem for Dreamcast VMU units)
 - VxFS
 - WAFL (NetApp's commercial file system)
 - Xiafs (Linux, dropped in favour of ext2)
 - XFS (SGI)
 - XtreemFS, (Linux, distributed file system)
 - YAFFS
 - ZFS
 
Networked and cloud filesystems
(Used to make files available to multiple systems over a local or wide area network, including "on the cloud" via the Internet; systems access files through a protocol or API. The low-level storage details, usually concealed from end users and even most developers, may be within one or more of the single-device filesystems above, and the networked/cloud filesystem is generally defined independently of such details and might have very different characteristics and rules as to how the files are named, addressed, and structured.)
- Andrew File System (Carnegie Mellon University)
 - Google Drive
 - Google File System
 - Hadoop Distributed File System
 - MEGA file system
 - NetWare File System (Novell NetWare, replaced by NSS)
 - NSS (Novell Storage Services)
 
Format details
- AppleDouble
 - AppleSingle
 - desktop.ini (Windows)
 - Desktop Services Store (Mac OS X)
 - MBR (Master Boot Record)
 - Resource Fork (MacOS)