The following tables display file extensions associated with system files, with extensions for the most commonly encountered file formats listed first:
| File Extension |
File Description |
| .ani |
Animated Cursor |
| .ann |
Help Annotations |
| .bmk |
Help Bookmarks |
| .cnt |
Contents File |
| .cur |
Windows Cursor |
| .dev |
Windows Device Driver |
| .dss |
DCC Active Designer File |
| .dvd |
DOS Device Driver |
| .ffa |
Microsoft Fast Find Status File |
| .ffl |
Microsoft Fast Find Document List |
| .ffo |
Microsoft Fast Find Document Properties Cache |
| .ffx |
Microsoft Fast Find Index |
| .fpbf |
Burnable Folder |
| .ftg |
Full Text Group |
| .fts |
Full Text Search |
| .gid |
Windows Help Index File |
| .grp |
Windows Program Manager Group |
| .icns |
Icon Resource |
| .ico |
Icon File |
| .idx |
Index File |
| .inf |
Setup File or Installer Script |
| .ins |
Internet Naming Service |
| .ion |
4DOS File Description |
| .isp |
IIS Internet Service Provider Settings |
| .its |
Internet Document Set |
| .kbd |
Keyboard Layout Script |
| .kext |
Mac OS X Kernel Extension |
| .key |
Security Key |
| .key |
Keyboard Definition File |
| .manifest |
Windows XP Visual Styles |
| .mdmp |
Windows Minidump |
| .msc |
Microsoft Management Console Snap-in Control File |
| .msp |
Windows Installer Patch |
| .nt |
Windows NT Startup File |
| .pdr |
Windows Port Driver |
| .plist |
Property List |
| .pol |
Windows Policy File |
| .pref |
Macintosh Preferences File |
| .prefpane |
Mac OS X System Preference Pane |
| .prf |
Windows System File |
| .pwl |
Windows Password List |
| .reg |
Registry File |
| .scf |
Windows Explorer Command |
| .scr |
Windows Screensaver |
| .sdb |
Custom Application Compatibility Database |
| .swp |
Swap File |
| .theme |
Desktop Theme |
| .vga |
VGA Display Driver |
| .vgd |
Generic CADD VGA Driver |
| .vxd |
Virtual Device Driver |
| .wdgt |
Dashboard Widget |
