The Basics
What most users don't seem to realize is that Mac
and PC compression programs are now cross-platform. If you're on a PC
and get an attachment with a .sit extension on the file name that means
it's a file compressed using the popular Mac utility program called
StuffIt. WinZip and other .zip compression/decompression programs for
the PC can decompress these files, and as long as the files they contain
are PC-friendly documents, you can open them as you would any other
PC files. If you're using a Mac and get a .zip attachment, StuffIt (which
comes with most Internet services, Web browsers, etc.) will open these
compressed documents without a hitch.
Tip: If you're sending documents from one computer type to another,
it's a good idea to add the appropriate three-letter file extension
to the documents. If you send a Microsoft Word .doc file from a Mac
to a PC without the .doc, the person on the other end may have trouble
opening it. On the receiving end, if you have trouble opening a file
by double-clicking on it, try opening up the application it was created
in and then opening the document from there.
Multimedia Files
Besides word processing documents, most of
what you get in attachments are graphics and audio files. Most every
graphic format (.gif, .jpg, .tga, .png, .bmp) can be opened (on either
a Mac or PC) with an image-processing program such as Photoshop. Multimedia
players, such as the Microsoft Media Player (which comes with both Mac
and PC versions of Internet Explorer) can handle both video formats
(.mpg, .avi, .qt, and .mov), as well as many popular audio formats (.mpg,
mp3, .ram).
Tip: If you get a file attachment and you're not sure what it is,
try opening it in your decompression program, Photoshop, MS Media Player
and MS Word. One of these programs will likely do the trick.
Other Formats
Here are a few other file formats you may encounter
and what to do with them:
- File Extension: .pdf
What is it?: Page Definition Format. A cross-platform format for viewing word/image documents
How to Open (PC): Use the .pdf viewer, Adode Acrobat, available for free
How to Open (Mac): Use the .pdf viewer, Adode Acrobat, available for free
- File Extension: .dcr, .dir, .dxr, .swf
What is it?: Director or Shockwave animation file
How to Open (PC): Simply drag the file onto a Web browser window and it will launch (as long as you have the appropriate plug-in)
How to Open (Mac): Simply drag the file onto a Web browser window and it will launch (as long as you have the appropriate plug-in)
- File Extension: .hqx
What is it?: Bin-Hex, a Mac binary compression format
How to Open (PC): Use WinZip or other .zip decompression program.
How to Open (Mac): Use StuffIt or StuffIt Expander
- File Extension: .sea
What is it?: A self-extracting Mac-formatted compression file
How to Open (PC): Use a .zip decompression program
How to Open (Mac): Simply double-click it
- File Extension: .rtf, .rtx
What is it?: Rich Text Format
How to Open (PC): Open through your word processing program
How to Open (Mac): Open through your word processing program
- File Extension: .xls, .xll
What is it?: Microsoft Excel
How to Open (PC): Open in MS Excel, in another spreadsheet program, or in MS Word
How to Open (Mac): Open in MS Excel, in another spreadsheet program, or in MS Word
- File Extension: .pcd
What is it?: Kodak PhotoCD image
How to Open (PC): Open in graphics program
How to Open (Mac): Open in graphics program
- File Extension: .exe
What is it?: Executable PC program
How to Open (PC): Double-click to launch it
How to Open (Mac): This is a PC program that you can?t run unless you have Windows emulation software installed
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TIP: If you get an attachment that you weren't expecting, and
the accompanying message is rather vague about its content ("Check
out this program!"), be suspicious -- even if it's from someone
you know. Current virus programs exploit people's address books and
send generic messages and attachments to the addresses contained within.
If you launch the attachment, the virus becomes active. It doesn't hurt
to write the person back and ask: "Mom, did you really send me
this Anna Kournikova pin-up pic?" Be especially wary of attachments
that end in .exe and .vbs (Visual Basic Script), both popular virus
carriers.
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