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Ever get an email attachment or see a file and not know what program
to use for it? Most of the time your computer will figure it out so when
you double-click on it, the necessary program will open it up. The extension
on the file (what comes after the "." dot), gives a hint as
to what the file type is so you know what program you can use to open
the file (or if it's a system file you shouldn't mess with) but these
days many operating systems will hide "known" file extensions.
In this case, "known" means your operating system can identify
the file type and should be able to open it. However, you may still want
to see the file extensions so you know what the files are too.
To set your Mac (using OSX) to always show file extensions,
- Click on Finder, Preferences, Advanced tab
- Check the Show all file extensions box.
To set your PC (using Windows XP) to always show file extensions,
- Start, Control Panel, double-click
on Folder Options (Classic view) or Appearance
and Themes then click Folder Options
(Category View)
- Click on the View tab.
- Uncheck the box that says Hide file extensions for known file
types.
To set your PC (using Windows 2000) to always show file extensions,
- Start, Settings, Control
Panel, double-click on the Folder Options
icon.
- Click on the View tab.
- Uncheck the box that says Hide file extensions for known file
types.
Once you know what the file type is, you can do a search on the Internet
to determine what software is necesary or best to open the file and even
if you don't have the necessary program to open it right away, you can
keep the file until you do or request the file in a different format (i.e.
it came in Word but you don't have Word so ask for it in pdf format so
you can view it with the free Adobe Reader program).
The following table lists some of the more common file extensions and
what they are. After the table are links to web sites that list more file
extensions in a searchable format. There did not appear to be one site
that listed them all.
| Extension |
Definition/Usage |
| .accdb |
Access 2007 database file |
| .asp |
Active
Server Page; for web pages |
| .avi |
Audio
Video Interleave; movie file |
| .bmp |
Bitmap
graphics; picture file commonly created with Paint on Windows |
| .csv |
Comma
Separated Values file; set up
like a text file where columns are separated by a comma; can be
viewed with Word or Excel |
| .dll |
Dynamic
Link Library; a system file often
shared by many programs |
| .doc |
Document
text file created with Word (pre 2007 format) |
| .docm |
Word 2007Macro-enabled Document |
| .docx |
Word 2007 Document |
| .dot |
Document
Template; created with Word, used as a basis for
new documents (pre 2007 format) |
| .dotm |
Word 2007 Macro-enabled Document Template |
| .dotx |
Word 2007 Template |
| .eps |
Encapsulated
PostScript vector graphics; picture
file |
| .exe |
Executable
file; for programs that are self-starting like Excel, Access, Word
|
| .gif |
Graphics
Interchange Format; picture file
viewable on multiple platforms |
| .htm or .html |
Hypertext
Markup Language; for viewing web
pages |
| .jpeg, .jpe, .jpg
|
Joint
Photography Experts Group;
picture file |
| .lbd |
Database
file, contains record-locking information for when
you have a MS Access database open. |
| .mdb |
Microsoft
database file; used by Microsoft
Access (pre 2007 format) |
| .mov |
Apple QuickTime Movie
|
| .pdf |
Portable
Document Format; file format most
computers can read with the Adobe Reader program |
| .php |
Hypertext
PreProcessor; for web pages |
| .potm |
PowerPoint 2007 Macro-enabled Presentation Template |
| .potx |
PowerPoint 2007 Template |
| .pps |
PowerPoint
Slide show (pre 2007 format) |
| .ppsm |
PowerPoint 2007 Macro-enabled Slide Show |
| .ppsx |
PowerPoint 2007 Slide Show |
| .pptm |
PowerPoint 2007 Macro-enabled Presentation |
| .pptx |
PowerPoint 2007 Presentation |
| .rtf |
Rich
Text Format; text file that can
be opened with any text editor or word processor |
| .sit |
Stuffitt
archive; compressed file |
| .tif, .tiff |
Tagged
Image File Format; high-end
picture file |
| .txt |
Text
file that can be opened with any text editor or word processor |
| .wav |
Waveform
audio file; sound file |
| .wpd |
Word
Perfect Document |
| .xls |
Excel
Spreadsheet (pre 2007 format) |
| .xlsm |
Excel 2007 Macro-enabled Workbook |
| .xlsx |
Excel 2007 Workbook |
| .xltm |
Excel 2007 Macro-enabled Workbook Template |
| .xltx |
Excel 2007 Template |
For more complete lists or to do a search, check out any or all of the
following sites:
- http://www.webopedia.com/quick_ref/fileextensionsfull.asp
- http://www.file-ext.com
- http://www.fileinfo.net/
Page last updated 11/29/07. Send questions or comments to ITS Training.
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