What Is a Filing Extension?

Windows system files are divided into many types according to different formats and uses. To facilitate management and identification, when naming files, they are distinguished by extensions, that is, the file name format is: "main file name. Extension". In this way, you can determine the type of file based on the file extension, and know its format and use.

Common file extensions

ISO:

A Common file extensions beginning with A

Extension description
A: Object code library file
AAM: Authorware shocked file
AAS: Authorware shocked package
ABF: Adobe Binary Screen Font
ABK: CorelDRAW Automatic Backup File
ABS: This type of file is sometimes used to indicate an abstract (just like an abstract or synopsis in a scientific article, taken from abstract)
ACE: Ace Compressed File Format
ACM: Windows System Catalog File
ACP: Microsoft Office Assistant Preview File
ACT: Microsoft office assistant file
AD: After Dark Screen Saver
ADA: Ada source file (non-GNAT)
ADB: Ada source file body (GNAT); HP100LX organizer's contract database
ADF: Amiga Disk File
ADI: AutoCAD Device Independent Binary Plotter Format
ADM: After Dark multi-module screen saver; Windows NT policy template
ADP: FaxWork interactive installation file for fax modem; Astound Dynamite file
ADR: After Dark random screen saver; Smart Address's address book
ADS: Ada Source File Specification (GNAT)
AFM: Adobe's Font Scale
AF2 / AF3: ABC's FlowChat file
AI: Adobe Illustrator format graphics
AIF / AIFF: Audio Interchange File, Sound Format for Silicon Graphic and Macintosh Applications
AIFC: Compressed AIF
AIM: AOL Instant Messaging
AIS: ACDSee graphic sequence file; Velvet Studio equipment file
AKW: All A-keywords in RoboHELP's help project
ALB: JASC Image Commander Photo Album
ALL: Art and Letters Library
AMS: Velvet Studio Music Module (MOD) file; Extreme Tracker module file
ANC: Canon Computer's palette file containing a series of optional color palettes
ANI: Animated Cursor in Windows
ANS: ANSI text file
ANT: Game files saved in SimAnt For Windows
API: Application design interface file used by Adobe Acrobat
APS: Microsoft Visual C ++ file
APK: Android installation package
ARI: Aristotle Sound File
ARJ: Robert Jung ARJ archive file
ART: Xara Studio painting files; Canon Crayola art files; Clip Art file format; another ray tracing format; marker files compressed by Johnson-Grace compression algorithm used by AOL
ASA: Microsoft Visual InterDev file
ASC: ASC text file; PGP algorithm encrypted file
ASD: Auto-save file of Microsoft Word; description file of Microsoft advanced streaming format (ASF); Velvet Studio example file can be opened with NSREX
ASE: Velvet Studio Sample File
ASF: Microsoft Advanced Streaming Format File
ASM: assembly language source files, Pro / E assembly files
ASO: Astound Dynamite Object File
ASP: dynamic web file; ProComm Plus installation and connection script file; Astound introduction file
ASV: DataCAD automatically saves files
ASX: Cheyenne backup script file; Microsoft Advanced Streaming Redirector file, video file
ATW: Any Time Deluxe For Windows Personal Information Administrator File from Personal Software
AU: Sun / NeXT / DEC / UNIX sound file; audio U-Law (read as "mu-law") file format
AVB: Computer Associates Inoculan Anti-Virus Virus File
AVI: Microsoft Audio Video Interleave movie format
AVR: Audio Visual Research File Format
AVS: Application Visualization Format
AWD: FaxVien Document
AWR: Telsis Digital Storage Audio File Extension Format
Axx: Sub-package serial number file of ARJ compressed file, used to compress a large file into several small compressed packages (xx takes the number 01-99)
A3M / A4M: Authorware Macintosh Unpacked File
A4P: Authorware Runtime-Free Packaged File
A3W / A4W / A5W: Unpackaged Authorware Windows File

B Common file extensions beginning with B

Extension description
BAK: backup file
BAS: BASIC source file
BAT: batch file
BDF: West Point Bridger Designer file
BGL: Microsoft Flight Simulator Vision File
BI: binary files
BIF: Group Wise initialization file
BIFF XLIFE 3D format file
BIN binary
BK / BK $ is sometimes used to represent backup versions
BKS IBM BookManager Read Bookshelf File
BMK bookmark file
BMP Windows or OS / 2 bitmap file
BOOK Adobe FrameMaker Book file
BRX for viewing files in a multimedia object directory
BSP Quake Graphics File
Batch files used by the BTM Norton application
BUD Quicken backup disk
BUN CakeWalk sound bundle file (a MIDI program)
BW SGI black and white image file
BWV Commercial Wave File

C Common file extensions starting with C

Extension description
CC code file
CAB Microsoft Compressed File
Drafix CAD files for CAD Softdek
CAL CALS compressed bitmap; calendar schedule data
CAP compressed music file format
CAS comma separated ASC file
CB Microsoft Clean Boot File
CC Visual dBASE user-defined class file
CCB Visual Basic Dynamic Button Configuration File
CCH Corel chart file
CCO CyberChat Data File
CCT Macromedia Director Shockwave Projection
CDA CD audio track
CDF Microsoft Channel Definition Format File
CDI Philip's high-density disk interactive format
CDM Visual dBASE Custom Data Module File
CDR CorelDRAW drawing file; raw audio CD data file
CDT CorelDRAW template
CDX CorelDRAW compressed drawing file; Microsoft Visual FoxPro index file
CFG configuration file
CGI common gateway interface script file
CGM computer graphics metafile
CHK File fragmentation saved by Windows Disk Defragmenter or ScanDisk
CHM compiled HTML file
CHR character set (font file)
CIF Adaptec CD Creator CD image file
CIL Clip Gallery download package
CLASS Java class file
CLL Crick Software Clicker file
CLP Windows Clipboard File
CLS Visual Basic Class File
CMF Corel Metafile
CMV Corel Move Animation File
CMX Corel Presentation Exchange image
CNF Telnet, Windows and other configuration files used by applications whose format changes
CNM Windows application menu options and installation files
CNT Windows (or other) system used to help index or other purpose content files
COD Microsoft C compiler displayable machine code / assembly code file with source C code as a comment
COM command file (program)
CPL Control Panel Extension, Corel Color Plate
CPO Corel print storage file
CPP C ++ code file
CPR Corel provides instruction file
CPT Corel Photos-Painting Images
CPX Corel Presentation Exchange
CRD Windows Cardfile
CRP Corel runtime introduction file; Visual dBASE custom report file
CRT Certification Document
CSC Corel script file
CSP PC Emcee On_Screen image
CST Macromedia Director Cast file
CSV comma-separated value file
CTL is usually used to represent a file containing control information; it is used by FaxWork to hold information about each fax received or sent
CUR Windows cursor file
CV Corel version archive; Microsoft CodeView info screen file
CXX C ++ source code files

D Common file extensions beginning with D

Extension description
DAT data files; WrodPerfect merged data files; for some MPEG format files
DB Borland's Paradox 7 table
DBC Microsoft Visual FoxPro Database Container File
DBF dBASE file
DBX DataBearn image; Microsoft Visual FoxPro form file
DCM DCM module format file
DCS Desktop Color Delimited File
DCT Microsoft Visual FoxPro Database Container
DCU Delphi compilation unit file
DCX Microsoft Visual FoxPro database container; PCX-based fax image; macro
DEM file used to represent the USGS datum of the digital height model
DER certification
DEWF Macintosh Sound Cap / Sound Edit recording device format
DIB device independent bitmap
DIC Catalog
DIF data interchangeable spreadsheet
DIG DigiLink format; Sound Designer audio file
DIR Macromedia Director file
DIZ description file
DLG C ++ dialog script file
DLL dynamic link library
DLS downloadable sound files
DMD Visual dBASE Data Module File
DMF X-Trakker Music Module (MOD) File
DOC Word document
DOT Microsoft Word document template
DRAW Acorn object-based vector image file
DRV driver
DRW Micrografx Designer / Draw; Pro / E drawing file
DSF Micrografx Designer VFX file
File saved by DSG DOOM
DSM Dynamic Studio Music Module (MOD) File
DSP Microsoft Developer Studio project file
DSQ Corel QUERY (Query) File
DSW Microsoft Developer Studio workspace file
DTD SGML Document Type Definition (DTD) file
DUN Microsoft dial-up network export file
DV Digital Video File (MIME)
DXF interchangeable drawing file format, binary DWG format text representation; data exchange file
DXR Macromedia Director protected (non-editable) movie files

E Common file extensions beginning with E

Extension description
EDA Ensoniq ASR Disk Image
EDD element definition document (FrameMaker + SGML document)
EMD ABT Expansion Module
EMF Windows Enhanced Metafile
EML Microsoft Outlook Express Mail Message (MIME RFC822) File
EPHTML Perl explains enhanced HTML files
EPS compressed PostScript image
EXE executable file (program)

F Common file extensions beginning with F

Extension description
FAV Microsoft Outlook Navigation Bar
FAX fax type image
FCD Virtual CD-ROM
FDF A dobe Acrobat form document file
FFA / FFL / FFO / FFK Microsoft Quick Find File
FIF Fractal image file
FLA Macromedia Flash Movie
FLC Autodesk FLIC Animation File
PLI Autodesk FLIC Animation
FM Adobe FrameMaker Document
FML file mirror list (GetRight)
FNG font set file (Font Navigator, Font Navigator)
FNK Funk Tracker module format
FON system font
FOT font related files
FRT Microsoft FoxPro report file
FRX Visual Basic form text; Microsoft FoxPro report file
FTG full text search group file, generated by the Windows help system when looking for it-can be deleted and rebuilt if needed
FTS full text search citation file, generated by Windows help system when finding

G Common file extensions beginning with G

Extension description
GAL Corel Multimedia Manager Photo Gallery
GDB InterBase Database File
GDM Ringtone, Whistle, and Soundboard Module Format
GEM GEM metafile
Text files generated by GEN Ventura
GetRight GetRight Unfinished Download File
GFI / GFX Genigraphics graphic link presentation file
GHO Norton clone disk image
GIF CompuServe bitmap file
GIM / GIX Genigraphics graphic link presentation file
GKH Ensoniq EPS Family Cluster Disk Image File
GKS Gravis Grip Key Document
GL animation format
GNA Genigraphics graphic link presentation file
GNT generated code, executable code in Micro Focus attribute format
GNX Genigraphics graphics link presentation file
GRA Microsoft Graph file
GRF Grapher (Golden Software) graph file
GRP Program Management Group
GO Go language source files

H Common file extensions beginning with H

Extension description
HCOM sound tool HCOM format
HGL HP Graphics Language Drawing File
HLP help files; Date CAD Windows help files
HPJ Visual Basic Help Engineering
HPP C ++ program header files
HST history file
HT HyperTerminal
HTM / HTML Hypertext Document
HTT Microsoft Hypertext Template
HTX Extended HTML Template

I Common file extensions beginning with I

Extension description
ICB Targa bitmap file
ICC Kodak Printer Format File
ICL Icon Library File
ICM graphic color matching profile
ICO Windows icon
IDD MIDI device definition
IDF MIDI device definition (files required by Windows 95)
IDQ Internet Data Query File
IDX Microsoft FoxPro related database index file; Symantec Q & A related database index file; Microsoft Outlook Express file
IFF interchange format file; Amiga ILBM
IGES Initial Graphics Exchange Documentation
IGF insert system metafile
ILBM bitmap graphic file
IMA WinImage Disk Image File
INF information file
INI initialization file
INRS INRS telecommunications audio
INS InstallShield installation script
INT intermediate code, when a source program is compiled and checked to produce an executable code
IQY Microsoft Internet Query File
ISO lists files on CD-ROM according to ISD 9660 standard for CD-ROM file system
IST Digital Tracking Device File
ISU InstallShield uninstall script
IWC Install Watch document

J Common file extensions beginning with J

Extension description
J62 Ricoh Camera Format
JAR Java Archive
JAVA Java source files
JBF Paint Shop Pro image browsing file
JFF / JFIF / JIF JPEG files
JMPDiscovery Form Statistics File for JMP SAS
JPE / JPEG / JPG JPEG graphic file
JS Javascript source file
JSP HTML page with a reference to a Java servlet
JTF JPEG bitmap file

K Common file extension K

Extension description
K25 Kurzweil 2500 Sample File
KAR karaoke MIDI files
KDC Kodak light booster
KEY DataCAD icon toolbar file
KFX KoFak Group 4 image file
KIZ Kodak Digital Postcard File
KKW RoboHELP helps the engineering index designer to start with all keywords that have nothing to do with K
KMP Korg Trinity KeyMap file
KQP Konica Camera Local File

L Common file extensions beginning with L

Extension description
LAB Visual dBASE tag file
LBM Deluxe Paint bitmap file
LBT / LBX Microsoft FoxPro tag file
LDB Microsoft Access Lock File
LDL Corel Paradox distribution library
LEG Legacy documentation
LFT 3D Studio (DOS) Stakeout File
Logo file for LGO Paintbrush (Microsoft Paint Application)
LHA LZH Replace File Suffix
LIB library file
LIN DataCAD linear file
Output file from LIS Structured Query Report (SQR) program
LLX Laplink Exchange Agent
LNK Windows Shortcut File
LOG log file
LST list file
LU ThoughtWing library unit file
LYR DataCAD layer file
LZH LH ARC Compressed File
LZS Skyroads data file

M Common file extension M

Extension description
M1V MPEG related files (
M3U MPEG URL (MIME sound file)
MAD Microsoft Access module file
MAF Microsoft Access form file
MAM Microsoft Access Macro
MAP mapping files; Duke Nukem 3D WAD game files
MAQ Microsoft Access query file
MAR Microsoft Access report file
MAT Microsoft Access table; 3D Studio MAX material library
MB1 Apogee Monster Bash Data File
MBX Microsoft Outlook saves email format; Eudora mailbox
MCR DataCAD keyboard macro file
MDB Microsoft Access database
MDE Microsoft Access MDE file
MDL Digital Tracker Music Module (MOD) file; Quake module file
MDN Microsoft Access empty database template
MDW Microsoft Access Workgroup File
MDZ Microsoft Access Wizard Template File
MIC Microsoft Image Composer file
MID MIDI Music
MIM, MIME, MME Internet mail extension format multi-purpose file, often as a file created in AOL attachment when sending e-mail; files in a multi-zone MIM file can be opened with WinZip or other similar programs
MLI 3D Studio Material Library Format File
MNG multi-image network graphics
MNU Visual dBASE menu file; Intertel Systems Interact menu file
MOD Fast Tracker, Star Trekker, Noise Tracker (and more) music module files; Microsoft multi-plan spreadsheets; Amiga / PC track files
MOV QuickTime for Windows Movie
MP2 Layer 2 MPEG Audio File
MP3 Layer 3 MPEG Audio File
MPA MPEG related files, MIME "mpeg type"
MPE / MPEG / MPG MPEG animation file
MPP Microsoft project file; CAD drawing file format
MPR Microsoft FoxPro menu (compiled)
MSG Microsoft Mail Message
MSI Windows installation package
MSN Microsoft Web Documentation; Descent Mission File
MSP Microsoft Paint (paint) bitmap file; Windows Installer path file
Files with MST Windows Installer
MTM Multi Tracker Music Module (MOD) file

N Common file extensions beginning with N

Extension description
NAN Nanoscope file (Raw Grayscale)
NAP NAP Metafile
NCB Microsoft Developer Studio file
NCD Norton changes directory
NCF NetWare command file; Lotus Notes internal clipboard
NFF neutral file format
NFT NetObject Fusion template file
NIL Norton cursor library file (EasyIcons-compatible)
NIST NIST Sphere Sound
NLS national language support files for localization (for example, Uniscape)
NLU Norton Live Update e-mail trigger file
NTX CA-Clipper Index File
NWC Noteworthy Composer Song File
NWS Microsoft Outlook Express News

O Common file extensions beginning with O

Extension description
OBJ object file
OCX Microsoft Object Linking and Embedding Custom Controls
ODS Microsoft Outlook Express mailbox file
OFN Microsoft Office FileNew file
OFT Microsoft Outlook Template
OLB OLE Object Library
OLE OLE Object
OOGL object-oriented graphics library
OPO OPL output executable

P Common file extension P

Extension description
P65 PageMaker 6.5 file
PAB Microsoft Personal Address Book
PART Go! Zilla partial download file
PAS Pascal source code
PY Python source code
PYC Python bytecode file
PYW Python graphics window file
PBD PowerBuilder dynamic library as an alternative to native DLL
PBL for PowerBuilder dynamic library in PowerBuilder development environment
PBM exportable bitmap
PBR PowerBuilder Resources
PCD Kodak Photo-CD image; P-Code compiler test script, tested by Microsoft and Microsoft Visual
PCL Hewlett-Packard printer control language file (printer spare bitmap)
PCM sound file format; OKI MSM6376 synthesis chip PCM format
PDD Graphic image that can be opened with Paint Shop Pro or other image processing software
PDF Adobe Acrobat exportable document format file (displayable by web browser); Microsoft Systems Management Server package definition file; NetWare printer definition file
PFM printer font scale
PGL HP Plotter Drawing File
PGM can output grayscale image (bitmap)
PH temporary file generated by the Microsoft help file compiler
PHP / PHP3 HTML pages with PHP scripts
PHTML HTML pages containing PHP scripts; HTML interpreted by Perl
PIC PC drawing bitmap; Lotus picture; Macintosh PICT drawing
PJX / PJT Microsoft Visual FoxPro Project File
PKG Microsoft Developer Studio application extension (similar to DLL file)
PNG Portable Network Graphic Bitmap; Paint Shop Pro Browser Catalog
POT Microsoft Powerpoint module
PPA Microsoft Powerpoint Interposer
Pinnacle program files for PPF Turtle Beach
PPM Portable Pixel Map Bitmap
PPS Microsoft Powerpoint Slide Show
PPT Microsoft Powerpoint presentation
PRF Windows system files, Macromedia director settings files
PRG dBASE Clipper and FoxPro program source files; WAVmaker program
PRJ 3D Studio (DOS) project file
PRN print form (space-separated text); DataCAD Windows printer file
PRT print format file; Pro / ENGINEER component file
PSD Adobe photoshop bitmap file
PSP Paint Shop Pro image file
PST Microsoft Outlook Personal Folder File
PWZ Microsoft Powerpoint Wizard

Q Common file extensions beginning with Q

Extension description
QIC Microsoft backup file
QIF QuickTime related image (MIME); Quicken import file
QLB Quick library
QRY Microsoft Inquiry File
QTP QuickTime Priority File
QTX QuickTime related images
QW Symantec Q & A Write program file

R Common file extensions beginning with R

Extension description
RA RealAudio sound file
RAM RealAudio Metafile
RAR RAR archive (Eugene Roshall format)
RDF resource description framework file (involving XML and metadata)
REG registry file
REP Visual dBASE report file
RES Microsoft Visual C ++ resource file
RFT editable form text (part of IBM's DCA or part of the document content framework structure)
RGB / SGI Silicon Graphics RGB File
RM RealAudio Video File
RMD Microsoft RegMaid Document
RPT Microsoft Visual Basic Crystal report file
RTF Rich Text Format Document
Extensions used by RUL InstallShield
RVP Microsoft Scan Configuration File (MIME)

S Common file extensions starting with S

Extension description
S assembly source code file
SAV game save file
SBL Shockwave Flash Object File
SCC Microsoft Source Safe file
SCF Windows Explorer command file
SCP dial-up network script file
SCR Windows screen saver; fax image; script file
SCT SAS directory (DOS); Scitex CT bitmap; Microsoft FoxPro form
SCX Microsoft FoxPro Form File
SDT SmartDraw template
SDV semicolon-separated value file
SDX Standard File for SDX Compressed MIDI Sample Dump
SEP Tag Image File Format (TIFF) bitmap
SFD SoundStage sound file data
SFI Sound Stage sound file information
SFR Sonic Foundry Sample
SFX RAR self-extracting file
SGML Standard Generalized Tag Language
SHG hotspot bitmap
SHTML HTML file with server-side include (SSI)
SHW Corel Show presentation
SIG symbol file
SKA PGP key
SKL Macromedia Director Resource File
SL PACT Save Layout Extension
SO Linux shared library
SPL Shockwave Flash object; DigiTrakker sampling
SQC Structured Query Language (SQR) plain code file
SQR Structured Query Language (SQR) program file
STR screen saver file
SWA Shockwave Sound File in Macromedia Director File (MP3 File)
SWF Shockwave Flash Object
SYS system file
SYW Yamaha SY Series Wave File

T Common file extensions beginning with T

Extension description
TAZ UNIX gzip / tape archive
TGA Targa bitmap
THEME Windows Desktop Theme File
THN Graphics WorkShop for Windows sketch
TIF / TIFF Tagged Image File Format (TIFF) bitmap
TIG tiger file used by the US government to distribute maps
TLB OLE Type Library
TMP Windows temporary files
TOL Kodak Photo Enhancer
TPL CakeWalk sound template file; DataCAD template file
TRM terminal file
TRN MKS Source Integrity Engineering Usage Log File
TTF TrueType font file
TXT ASC sound data in text format
TXW Yamaha TX16W Wave File

U Common file extensions beginning with U

Extension description
UDF Windows NT / 2000 Unique Database File
ULT Ultra Tracker Music Module (MOD) file
URL Internet Shortcut File
USE MKS source integrity file
UWF Ultra racker wave file

V Common file extensions beginning with V

Extension description
VBP Microsoft Visual Basic project file
VBS Microsoft Visual Basic scripting language
VBW Microsoft Visual Basic workspace file
VBX Microsoft Visual Basic user-defined control
VCT / VCX Microsoft FoxPro Class Library
VDA Targa bitmap
VIR Norton Anti-Virus or other antivirus products are used to identify files infected by a virus
VIV VivoActive Player streaming video files
VSD Visio drawing file (flow chart or diagram)
VSL Download List File (GetRight)
VSS Visio template file
VST Targa bitmap
VSW Visio Workspace File
VXD Microsoft Windows Virtual Device Driver
VBP Microsoft Visual Basic project file
VBW Microsoft Visual Basic workspace file
VBX Microsoft Visual Basic user-defined control
VDA Targa bitmap
VIR Norton Anti-Virus or other antivirus products are used to identify files infected by a virus
VQF Yamaha Sound-VQ file (standard may appear)
VSD Visio drawing file (flow chart or diagram)
VSL Download List File (GetRight)
VSS Visio template file
VST Targa bitmap
VSW Visio Workspace File
VXD Microsoft Windows Virtual Device Driver

W Common file extensions beginning with W

Extension description
W3L W3Launch file
WAB M icrosoft Outlook file
WAD Large files of DOOM games containing videos, player levels and other information
WAV Windows Waveform
WBK Microsoft Word backup file
WCM WordPerfect Macro
WDB Microsoft Works Database
WFM Visual dBASE Windows Form
WFN symbols used in CorelDRAW
WIL WinImage file
WIZ Microsoft Word Wizard
WLL Microsoft Word interposer
WMF Windows Metafile
WOW Grave Composer music module (MOD) file
WP WordPerfect document
WPD WordPerfect document or presentation
WPF Word Processing Document
WPG WordPerfect graphics
WPS Microsoft Works Document
WPT WordPerfect template
WR1 Writer Document
WRK Cakewalk Music Sound Project File
WRL virtual reality model
WRZ VRML file object

X Common file extension X

Extension description
X AVS image format
XAR CorelXARA Painting
XBM MIME "xbitmap" image
XI Scream Tracker Device Sample File
XLA Microsoft Excel interposer
XLB Microsoft Excel toolbar
XLC Microsoft Excel charts
XLD Microsoft Excel dialog
XLK Microsoft Excel backup
XLL Microsoft Excel interposer file
XLM Microsoft Excel Macro
XLS Microsoft Excel worksheet
XLT Microsoft Excel template
XLV Microsoft Excel VBA module
XLW Microsoft Excel Workbook / Workspace
XNK Microsoft Exchange Shortcut File
XPM X bitmap format
XWD X Windows Dump Format
XWF Yamaha XG Works file (MIDI sequence)
X16 macro media expansion (program expansion), 16-bit
X32 macro media expansion (program expansion), 32-bit

Y Common file extensions start with Y

Extension description
YAL Arts & Letters Clip Art Gallery

Z Common file extensions starting with Z

Extension description
Z UNIX gzip file
ZAP Windows Software Installation Configuration File
ZIP Zip file

IN OTHER LANGUAGES

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