This forum is dedicated to the productivity application, AppleWorks. It is not a "catch-all" for how Apple computers work.
.dat is a Windows file & the best info I could find with a Google search is
this explanation. If you want to open it on a Mac, you might try TextEdit which is in your Applications folder.
Contact the file creator and ask them what application was the file created with. We can then tell if there is a converter for it. You may find one on my FAQ*:
Actually, I must disagree with Peggy, not all .dat files are Windows files. In fact, if you often use Spotlight, you may find .dat files all over your mac embedded within many applications(found over 40 on mine alone). For instance, WritersCafe uses .dat files to contain an entire project's data.
Consequently, AppleWorks uses .dat files as well for things such as spreadsheets.
DAT files are data files and are not absolutely Microsoft.
My question to you would be, What is the .dat file supposed to be? Is it a winmail.dat which you received randomly in an email? If it is, disregard it as most winmail.dat files are from people using Microsoft Outlook and the file is only for formatting in the email message. If you arent using Outlook, the email message will never look the way it was formatted so just disregard it.
If the file is from Appleworks and you dont have it, have the person you received the file from, export the file to something readable like .csv (comma separated values)and then import it into another program such as Excel!
On the other hand, if you are trying to read the file in Appleworks and the .dat file was created for another program, you may have a problem with formatting. You really need to find out what program created the .dat file and let us know here so we may be able to help further.
While Timothy Mallon is correct in stating that not all .dat files are Windows files, I question his statement that
"Consequently, AppleWorks uses .dat files as well for things such as spreadsheets."
There are 241 files on my iBook with the .dat suffix. Although I use AppleWorks daily, and it is my primary application for word processing, database, drawing and spreadsheet tasks, not one of these .dat files gives any indication that it was created by AppleWorks.