File extensions are the letters after the period in a filename for example the ".doc" part of the filename "GreatAmericanNovel.doc " in your computer. These filenames are required by Widows computers to determine which application should open the file when it is double-clicked.
Macintoshes do not require filename extensions but will use them if they are provided (for example in a file sent from a PC.) Macs have another way to determine which Application should open the file, the user has control over this and can change the application in the Get Info window for the file. The Get Info window is opened by selecting the file and then using [Command]-I on the keyboard amongst other methods.
| Extention |
File type |
Application(s) |
Comments |
| .cwk |
Text |
AppleWorks
ClarisWorks |
Can be opened in Pages or TextEdit but not completely |
| .doc |
Text
Word Processor |
MicroSoft Word |
Can be opened in Pages or TextEdit but not completely |
| .docx |
Text
Word Processor |
MicroSoft Word 2007 and later |
Can be opened in Pages or TextEdit but not completely. Cannot be opened in earlier versions of MS Word! |
| .pages |
Text
Word Processor |
Pages |
Part of Apple's iWork |
| .rtf |
Text
Word Processor |
Any Word Processor |
Rich Text Format - recommended for files to be transfered to other computers. |
| .rtfd |
Text
Word Processor |
Any Word Processor |
Rich Text Format with images - recommended for files to be transfered to other computers. |
| .pdf |
Portable |
Preview |
Portable Document File. Designed to contain Text, Graphics, and multimedia content and be readable on any computer system. Created from the Print option in most Mac Applications |
| .txt |
Text
Word Processor |
Any Word Processor |
Contains plain text and no graphics |
| .text |
Text
Word Processor |
Any Word Processor |
Contains plain text and no graphics |
| .zip |
compressed |
Zipeg
(freeware) |
Will self open on a mac |
| .sit |
compressed |
Stuffit
Expander
(freeware) |
Mac binary compression |
| .sea |
compressed |
Stuffit
Expander
(freeware) |
Mac binary compression - will self expand on a Mac |
| .bin |
compressed |
Stuffit
Expander
(freeware) |
Mac binary compression |
| .hqx |
compressed |
Stuffit
Expander
(freeware) |
Mac binary compression |
| .exe |
Windows |
none |
Windows executable or compression file. No good on a Mac |
| .jpg |
Graphic |
Preview and
any graphics application |
Common lossy compressed graphic format |
| .jpeg |
Graphic |
Preview and
any graphics application |
Common lossy compressed graphic format |
| .gif |
Graphic |
Preview and
any graphics application |
Graphics Interchange Format - Common lossless compressed graphic format, limited to 256 colors. |
| .png |
Graphic |
Preview and
any graphics application |
Portable Networks Graphics - Common lossless compressed graphic format. |
| .tiff |
Graphic |
Preview and
any graphics application |
Graphics Interchange Format - Common lossless compressed graphic format, high resolution large files. |
| .pict |
Graphic |
Preview and
any graphics application |
Apple graphic format that handles bitmap and vector graphics |
| .psd |
Graphic |
Adobe Photoshop |
|
| .psd |
Graphic |
Adobe Photoshop |
|
| .mov |
Video |
QuickTime |
Apple Format. Opens on most Movie applications |
| .mpg |
Video |
QuickTime |
Common Movie format. Opens on iTunes and iMovie |
| .mpeg |
Video |
QuickTime |
Common Movie format. Opens on iTunes and iMovie |
| .swf |
Video |
needs plugins on a Mac |
Adobe Flash format |
| .wmv |
Video |
Flip4Mac
(freeware plugin) |
Windows video. A number of plugins for Mac. |
| .htm |
Web Page |
Safari |
Hyper Text Markup Language. Text files opened in any web browser or text editor |
| .html |
Web Page |
Safari |
Hyper Text Markup Language. Text files opened in any web browser or text editor |
| .xml |
Web Page |
Safari |
Extensible Markup Language. Text files opened in any web browser or text editor |
| .aiff |
Audio |
iTunes |
Apple's high resolution audio format |
| .mp3 |
Audio |
iTunes |
Common Compressed format |
| .m4a |
Audio |
iTunes |
Common Compressed format |
| .wav |
Audio |
iTunes |
Windows format |
| .key |
Presentation |
KeyNote |
Apple format |
| .ppt |
Presentation |
PowerPoint |
Microsoft format |
| .dmg |
Disk image file |
OS-X |
Used to transfer data in a compressed form - Macintosh only. |
| .wdgt |
Widget |
Dashboard |
Widgets are small apps for the Dashboard application. |
| .plist |
Preferences |
|
Preference files for applications. Usually stored in the Library. Do not use them unless you know what you are doing. |
| .workflow |
Script |
Automator |
Scripts created with the Automator application to handle repetitious tasks. |
