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