Windows Guide

Guide to File Types

File types

Windows maintains a list of different file types based mainly on the file extension of the file and these are stored in the Registry. Every time you double click on a given file, Windows will know what file or program to load with that file. Not all files will open an application and these are special files used by windows or application programs as library files (DLL), data files or someother special function. These should not be opened or assigned to any program.

To view the file types of applications that are installed:

a) Enter a file type or link type in the search box at the top, for example, enter .doc, and it will display the associated application underneath, e.g. Microsoft Word.

b) In the Search apps box, enter name of the application, it will display the application, clicking on the arrow on the right will display the associated file type.s

c) Select an application from the list, and it will list all the associated file types underneath.

If the file is a known application file which can be opened then there are three ways you can allocated that file to an application:

a) Double click on the file and an Open With dialog box will appear and you can either choose a known program from the Internet or select a possible program from a list. Select the application from the list or click on Browse to choose another program not in the list. If you want it to be a permanent assignment then tick the box 'Always use the selected program to open this kind of file' (this box is unticked when a file has no extension).

b) If the file is already allocated to a program, then you can reassign it to a different program by selecting the file and pressing Shift key and pressing the right hand mouse button to bring up the pop up menu. The Open With option will appear and then you can assign the file to another program as before.

c) Select or search for the file type or program, e.g. Paint, then expand the program to view the associated file types, select the file type you want, e.g. .bmp, and a pop up window appear with a list of other programs you can associate it with e.g. Corel Paint Shop Pro.

To disassociate a file type from a program, you will have to use the Regedit tool and completely remove its entry under the HKEY_Current_User\Software\Microsoft\Windows\Currentversion\Explorer\FileExts or create a batch file and supply the extension as a parameter, as follows:

@echo off
ECHO Removing file extension %1
REG.EXE Delete HKCU\Software\Microsoft\Windows\Currentversion\Explorer\FileExts\%1 /f

Here is a short list of file types that you may come across (NB: Binary files look like garbage when viewed and should not assigned or deleted):

Extension Application Type of file
123 Lotus 123 Lotus 123 spreadsheet
7Z 7-Zip 7-Zip archive file
ACCDB Access Database file
APR Approach Approach database
BAK Any Backup file
BAS Visual Basic VB Program module
BAT None Batch file (text)
BIN None Binary file
BMP Photo viewer Bitmap Picture
CAB Winzip Cabinet archive
CHM DotCHM Compiled HTML Help
CL4 CreateCD CD Layout file
CLASS Java Java class program
COM None Program file (binary)
CPL Control Control Panel
CSS Any Style Sheet
CUR Mouse Cursor images
DAT Any Data file
DBF DBase Database file
DLL None Dynamic Link Library (binary)
DOC Word Word document
DOCX Word Word 2007+ document
EML Mail Email message
EXE None Program file (binary)
FON Fonts Bitmap font
FRM Visual Basic VB Form
FRX Visual Basic VB Form in binary
GID None Index file
GIF Photo viewer Picture file
HLP WinHelp Help file
HTM IExplore Web document (text)
HTML IExplore Web document (text)
ICO Paint Icon file (picture)
IFF Paint Interchangable File Format (picture)
INF None Device info file (text)
INI Notepad Program Initialisation (text)
JAVA Java Java source code
JPG Photo viewer JPEG Picture
JS Win Script Host Javascript file (text)
JSON Visual Studio Javascript object notation (text)
JWL Jewel CC CD Jewel Case layout
LOG Any Log file (text)
LNK Explorer File link or shortcut
LWP WordPro Lotus WordPro document
MAX PaperPort Paperport document
MDB Access Access Database
MOD Films & TV Music file
MOV Films & TV Movie file
MPG Media Player Mpeg video or audio file
MSI Windows installer Program installation file (binary)
MSP Installer Patch Program update (binary)
NLS None Codepage file (binary)
NWS Outlook Express Newsgroup message (text)
OCX None ActiveX Object (binary)
PDF Acrobat Portable document format
PHP PHP PHP: Hypertext Processor script
PIF PifEditor Program Info File (msdos)
PNG Photo viewer PNG picture
PPD Printer Printer Desc. file
PPT Powerpoint Powerpoint Presentation
PRN None Print File
PWL User Password file (binary)
PY Python Python script file
QDF Quicken Quicken Accounts data
QPW Quattro QuattroPro Spreadsheet
REG RegEdit Registry entries (text)
RTF Write Rich Text Format
SAV Any Saved file
SCR Display Screen Saver
SLN Visual Basic Project solution file (text)
SWP None Swap file (binary)
SYS None Device driver (binary)
TMP Any Temporary file
TTF Fonts TrueType font
TXT Notepad Text file
URL IExplore Web address shortcut
VBP Visual Basic VB Project
VBS Visual Basic Script file
VBW Visual Basic VB Workspace
WAV Media Player Wave audio file
WMF Paint Windows Meta File (picture)
WPD WordPerfect WordPerfect document
XLS Excel Excel Spreadsheet
XLSX Excel Excel 2007+ spreadsheet
XML Notepad XML Data file (text)
ZIP 7-Zip ZIPped archive



FTP FTP File Transfer Protocol
HTTP Web browser Hypertext transfer prootcol
HTTPS Web browser Hypertext transfer prootcol with security
LDAP Addess book Lightweight Directory Access Protocol
MAILTO Mail program Mail to protocol
MMS Media Player Microsoft Media Server
PCAST iTunes iTunes Podcast

CD Recording