The following are basic examples of file extensions and what they mean. This is by no means a complete listing, just a few of the more common file types.

The extension is the 3 letter identifier that appears at the end of a file name after the period ( commonly called 8 dot 3 naming routine) to tell you and any programs associated with that file type how to use it.

When you double click on the file the program associated with that type of file will start and display the file in that program.

Just by looking at the last 3 letters, you can tell what the file is by using the following chart.

For a list of Internet terms click here

  1. .arc
    Archive file, these are files compressed using the program ARC.
  2. .art
    Art file. A Johnson-Grace compression scheme that compresses graphics EXTREMELY well while still retaining good image quality.
  3. .avi
    Audio\Visual. These are windows video files.
  4. .bat
    Batch file. These are scripts that run in DOS, and are usually designed to automate tasks.
  5. .bmp
    Bitmap. A type of graphics file used by PC-Paintbrush that comes with windows and other programs.
  6. .com
    These are small programs for DOS. They are usually utilities, but not always.
  7. .dll
    Dynamic Link Library. These files give functionality to other programs. They usually need to be installed into the C:\windows\system directory. VBRUN300.dll is a good example.
  8. .doc
    Documents. This is the default file extension for Microsoft Word and some other programs. Most files with this extension will be Microsoft Word, but there are many that are plain text.
  9. .dot
    Document Template. These files are templates for Microsoft Word.
  10. .eps
    Encapsulated Postscript File. These are graphics images designed for Vector Graphics. Most drawing programs such as Aldus Freehand and Adobe Illustrator use this format.
  11. .exe
    Executable. This is an application. Most major programs end with this extension. It is also used for self-extracting archives, which are programs that when run explode into several smaller programs.
  12. .gif
    Graphics Interchange Format. This is a type of graphic image that is very common on online services and the internet.
  13. .jpg
    Joint Photographers Expert Group. A graphics format designed to take up as little space as possible while retaining as much quality as possible .Jpg's are smaller than .gif's, but take longer to display.
  14. .ini
    Initialization File. These files are used to set parameters and preference . Normally, these files should not be tampered with.
  15. .me
    This is a commonly used extension in DOS programs that tells you to do something. For example, you'll commonly see files named READ.ME or TYPE.ME and thats exactly what you should do with them.
  16. .mid
    Musical Instrument Digital Interface. MIDI files are songs for most sound cards and MIDI boards. There are different types, and not every .mid file will play on every sound card\midi board.
  17. .mod
    Music Modules. These are Amiga files that have been adopted by the PC community. They are music files that include the instruments as well as the score, and play through a sound card, NOT MIDI. You will need a special program to play these files.
  18. .pcx
    These are older graphics files commonly used for clip art.
  19. .scr
    Screen Saver. These are windows screen savers. To use them, copy the .scr file into the windows directory, and run the control panel and then the desktop applet.
  20. .sys
    System file. These are drivers used by Windows and DOS. Be sure to READ the file description and any accompanying documents carefully.
  21. .tif
    Tagged Image Format. These are bitmapped graphic images popular among desktop publishers.
  22. .ttf
    True Type Font. These are scalable fonts commonly used in windows. You will need to run the control panel to install them.
  23. .txt
    Plain text file and can be read by most programs, especially NOTEPAD.
  24. .wav
    Wave files. These are windows sound files. If you don't have a sound card you won't be able to hear the sound file.
  25. .wks (.wk1 .wk3)
    Worksheet files. These are Lotus 1-2-3 spreadsheet files. Most popular spreadsheet programs can display these files.
  26. .wp5
    Word Perfect 5.0 file. These files can be read by Word Perfect and many other popular word processing programs.
  27. .wpd
    Word Perfect 6.x file.
  28. .xls
    Excel spreadsheet file. Can be read by Microsoft Excel and some other spreadsheet programs.
  29. .zip
    ZIP Archive(PKZIP & WINZIP). This is the most common format for compressed files.