Common file extensions

Have you ever faced a file on microsoft windows ? sure .. There are several file types. The file extensions describe each file and specify

the type of it. For example Microsoft Word Documents takes the extension .DOC so that when you check the file you know that this is a

Microsoft Word Document. What are the file naming rules as well as what are the extension types ?

The file naming is divided into two categories : filename.ext where filename is the file name and ext is the extension name.

Formerly in MS-DOS The filename had the following restrictions is it composed form 1-8 characters and the extension from 0-3 characters. Now

the windows naming is different the filename could each 255 letters not more. The extension is almost kept about 3 letter for backward

compatibility but not in all cases sometimes it might exceeds 3 letters

Valid Naming Letters : A – Z ( all Caps and small letters ) 0-9 $ # & + @ ! ( ) – { } ‘ `_~ and the space
Invalid Naming Letters : |<>\\^=?/[]”;,* plus control characters

Take care sometimes you may find an attachement like the following example : ” README.TXT.VBS ” this file could harm your PC as it is a kind

of executable script that might have side effects on your PC.

to see the whole file extensions there are many steps on windows environment that is discussed on another topic

ASM Assembly Language File
ASP Active Server Page
AVI Audio Video Interleave File

BAS BASIC Source Code
BAS QuickBASIC Extended v7.1 Source
BAT Batch Processing (Microsoft)
BGI Borland Graphic Interface (Borland Software Corporation
BIN Binary File
BIN CDRWin CD Image File
BIN Linux Executable

C   C/C++ Program File
C  Check Point Site Configuration for Secure Remote
C   Origin C Program File (OriginLab)
C3D Micrografx
C3D Cult3D Designer Intermediate File
C3D Chem3D Chemical File (CambridgeSoft Corporation)
C4D Cinema 4D 3D Model (MAXON Computer GmbH)
CAB Install Shield v5.x or 6.x Compressed File (InstallShield Software Corporation)
CAB Cabinet File (Microsoft Corporation)
CAM Camtasia Studio Project/Producer Files (TechSmith Corporation)
CAP Sniffer Capture File (Network Associates Technology, Inc.)
CHM ChemDraw Chemical Structure (CambridgeSoft Corporation)
CHM HTML Help Compiled Help File (Microsoft Corporation)
COM Command
COM Common Object Module
COM DOS or CP/M Executable
CSV Comma-Separated Variables (Excel)
CTL User Control
CTL Visual Basic User-defined Control (Microsoft Corporation)

D3D Direct3D File
DA0 Windows 95/98 Registry Backup (Microsoft Corporation)
DBF Database
DOC Word DOT File (Microsoft Corporation)
DOC Document or Documentation
DOC Maybe and RTF File too
DOC Word Document (Microsoft Corporation)
DOC Palm Pilot DOC File Format
DOCX Word Microsoft Office Open XML Format Document (Microsoft Corporation)
DV Digital Video File
DWG AutoCAD Drawing Database (Autodesk, Inc.)

EXE Executable File (Microsoft Corporation)
EXE Self-extracting Archive
FLC Corel Show
FLC FLIC Animated Picture (Autodesk, Inc.)
FRM Oracle Executable Form
FRM Visual Basic Form
FRM WordPerfect Merge Form (Corel Corporation)
GMAX gmax Game Creator (Autodesk, Inc.)
GZ Gzip Compressed Archive
GZ GIMP Image File (The GIMP Team)

H   C/C++ Header file
HEX Hexadecimal Dump file
HFX Hollywood FX Special Effects File (Pinnacle Systems, Inc.)
HHK HTML Help Index (Microsoft)
HHS HTML Help Samples (Microsoft)
HHP HTML Help Workshop Project (Microsoft)
HLP Advisor Help File (Microsoft Corporation)
HLP Windows Help File (Microsoft)
HTM Hypertext Markup Language
HTML Hypertext Markup Language
HTML Mozilla (Netscape) Bookmark File (

ICO OS/2 Icon
ICO Sun Icon/Cursor
ICO Windows Icon (Microsoft Corporation)
IDX ICQ Index (ICQ Inc.)
IDX Index
IDX Outlook Express Mailbox Index (Microsoft)
ISO ISO-9660 CD Disc Image
ISO InstallShield Uninstall File (InstallShield Software Corporation)
ISO Easy CD Creator Disc Image (Sonic Solutions)
ISO Virtual PC Virtual CD-ROM Image (Microsoft)

J   Java Source Code (Sun)
JAD Java Application Descriptor File (Sun Microsystems, Inc.)
JAR Java Applet (Sun)
JAR Archive (ARJ Software, Inc.)
JAR Java Archive (Sun Microsystems, Inc.)
JPG CompactDRAW e-JPG Graphic (MediaChance)

KEY Business Key Accounting File (Universal Systems)
KEY AntiVir PersonalEdition License Key File (AntiVir PersonalProducts GmbH)
LIC License File  ( node also use it )
LNG Language File
LOG Log File
LST Listing or List
LZH Compressed Archive File
LZMA 7-Zip Compressed File (Igor Pavlov)
LZO lzop Compressed Archive
LZS Compressed Archive File
LZW Compressed Amiga Archive File
LZX Compressed File

M2A MPEG-2 Audio
M2V MPEG-2 Video Only File
MPG MPEG-1 / MPEG-2 Video File
M4V MPEG-4 Video File
MPG MPEG 1 System Stream
MPG MPEG Animation
MP4 MPEG-4 Media File
MID MIDI-sequention Sound
MOV QuickTime Video Clip (Apple Computer, Inc.)
NRG Nero CD-Image File (Nero AG)

OCX Object Linking and Embedding (OLE) Control Extension (Microsoft)

PAC Photo-CD Multi-resolution Image File
PAC Sound Blaster Studio II Package
PCL HP Printer Control Language (Hewlett-Packard Development Company, L.P.)
PHP PHP Script file
PNG Paint Shop Pro Browser Catalog (Corel Corporation)
PNG Fireworks Image File (Macromedia)
PNG Portable (Public) Network Graphic
PPS PowerPoint Slideshow (Microsoft Corporation)
PPT PowerPoint Presentation (Microsoft Corporation)
PRJ Project File
PRJ Visual Basic Project (Microsoft Corporation)
PSD Photoshop Format (Adobe Systems Inc.)

QTS QuickTime System File (Apple Computer, Inc.)

RAR WinRAR Compressed Archive (RarLab)
RES Resource File
RES C++ Compiled Resource (Borland Software Corporation)
RES C and C++ Compiled Resource (Microsoft)
RLE Run Length Encoded Bitmap
RPT Visual Basic Crystal Reports File (Microsoft Corporation)
RPT Report

SAV Saved File
SAV Daemon Tools Pro Disk Image (The Daemons Home)
SAV Backup
SAV Various Saved games for several games
SAV SPSS Database File (SPSS Inc.)
SAV Saved Configuration Info
SBS SPSS Script (SPSS, Inc.)
SCR Windows Screen Saver
SYS System Device Driver
SY_ Compressed SYS File

TLB SPSS Type Library (SPSS, Inc.)
TLB Visual C++ Type Library (Microsoft)
TMP Norton AntiVirus Backed Up File
TPU Turbo Pascal Compiled Unit (Borland Software Corporation)
TRC FCAccess Analyzer Trace File (Ancot Corporation)

UEZ COOL 3D (Ulead Systems, Inc.)
USR User Database

VB  VBScript File or Any VisualBasic Source
VBS VBScript Script File
VBS Visual Basic for Applications Script (Microsoft)
VHD Virtual PC Virtual Hard Disk (Microsoft)

W51 WordPerfect Ver. 5.1 Document (Corel Corporation)
W60 WordPerfect Ver. 6.0 Document (Corel Corporation)
W61 WordPerfect Ver. 6.1 Document (Corel Corporation)
WAD Famous ID Software games Archive files ( Wolf3D, Doom, Quake , Hexen and Heretic etc..)

X   Direct3D Object (Microsoft)
XLS Works Spreadsheet (Microsoft)
XLS Excel Worksheet (Microsoft Corporation)

YBK Encarta Yearbook

ZIP Compressed Archive File
ZNO Zinio Reader Magazine (Zinio Systems)


You can check more file types in the following link :