Common Internet file formats

Learn about common Internet file formats.

This article has been archived and is no longer updated by Apple.

Many of the file types listed in the table below can be handled directly by your Web browser. Sometimes a "helper application" is needed to open or use the file. Many of the multimedia file types listed below can be opened with QuickTime Player, Preview (Mac OS X) or PictureViewer (Mac OS 8, 9).

File suffix
Format description and type
How to use
.au This is a common sound format on the World Wide Web. Use QuickTime or Sound Player to play it.
.aiff Uncompressed sound format. Use QuickTime or Sound Player.
.bin MacBinary II encoded file. Make sure to download as MacBinary or Binary. Use Stuffit Expander to return to a usable Macintosh file (if it is not already).
.doc DOS/Windows file. Use MS-Word (or other text application).
.exe DOS/Windows program or a DOS/Windows self-extracting archive. Must be run on a PC (or a Macintosh with hardware- or software-based PC compatibility).
.gif GIF (Graphical Interchange Format). A common graphics file format. Use QuickTime, your web browser, Graphic Converter, Photoshop, GIFConverter, JPEGView.
.gz .gz is the Gnu version of zip. Used on UNIX systems. Use Stuffit Expander to extract archives, or macgzip to view and extract archives.
.html, .htm HTML (HyperText Markup Language), the code that web pages are formed with. A plain text file. Use your web browser or any text editor (like SimpleText).
.hqx BinHex. Encodes a Macintosh file into 7-bit text so it can be transferred across the Internet. Use Stuffit Expander to decode the file and return it to its original state.
.img Macintosh Disk Image. Use Disk Copy to mount the disk image on your Macintosh desktop. The mounted disk image will behave as a read-only disk.
.jpeg, .jpg, .jfif JPEG/JFIF, a graphic format. Use QuickTime, your web browser, or a graphics viewer such as JPEGView.
.mpeg, .mpg An MPEG movie. Use QuickTime Player.
.mp2, .mp3 MPEG Layer II and Layer III compressed audio. Use QuickTime Player or a third-party mp3 player.
.moov, .mov, .qt, .movie QuickTime movie. Use QuickTime Player.
.pdf Adobe Acrobat Portable Document Format. Download these files as binary. Use Adobe Acrobat Reader or Preview.
.ra, .ram, .rm RealNetworks audio or video Use RealPlayer.
.ps Postscript file. Plain text file. Send to a PostScript printer with the LaserWriter Font Utility or view it onscreen using Ghostscript.
.scr Disk Copy Script. Use Disk Copy.
.sea Macintosh self-extracting archive. Open it in the Finder.
.sit Stuffit Archive - Binary. Download as MacBinary, and use Stuffit Expander.
.smi A self-mounting image, created by Disk Copy. Similar to .img, but does not require the use of Disk Copy. Download the .smi file and open it. A disk image will appear on your desktop.
.tar UNIX tar program takes separate files and turns them into a single file. Extensions such as .tar.Z, .tar.gz and .tgz (latter two are equivalent) require decompression first, then un-tar. Extract with Stuffit Expander, or use Tar.
.tiff, .tif image format. Use QuickTime Player, Preview, JPEGView, or GraphicConverter.
.txt A plain text file. Use your web browser, or any text editor such as SimpleText.
.uu, .uue A uuencoded file. Use Stuffit Deluxe, UU Undo, or UUunencode to decode it.
.wav Windows Wave format sound. Use QuickTime Player.
.Z UNIX Compressed File. If you are downloading via ftp, most ftp servers will expand for you if you drop the ".Z". Otherwise, use Stuffit Expander with Expander Enhancer.
.zip pkzip, a common DOS/Windows compression format. Use ZipIt, Stuffit Expander, or MacUnZip.

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