What is a .Dat file in windows?

The most appropriate way of opening a .Dat extension file is to utilize the same application which created it. In case of uncertainty one can try out with notepad. After opening the file with notepad one may recognize some part of the data, however most of the remaining part would be unrecognizable and most probably junk ejected by the source program.
These files are normally found in emails with attachments. However programs of these days do not produce any .Dat file and it is usually being used by programmers only.
To search “What is a dat file” initially you must inquire about the file from the sender that which application was used for its creation. If their response has a sense that it was just mere document or picture file with some other extensions, and they are not sure how it turned into a .Dat file, then it means file extension was changed during the email routing process.
Actually it may appear odd, but some email server programs change the extensions of attached to .Dat files automatically. Therefore if you were supposed to receive an image file, all you need to do is to change the extension of the file to JPG, PNG or GIP whichever you think would be more appropriate. A Microsoft word file should be changed to extension .Doc.
To change the file extension select Tools under File Options in windows explorer.
Then select the View tab and keep scrolling down until the option “Hide extensions for known file types” appears. Uncheck it to see the extension of all the files in that folder which you can change to something else.
All you need to do is right click over the file and change the extension which appears after the dot to any preferred format.
Finally, you must observe that change of icon of the file, representing the application which can open it. Like for an Excel sheet it should be an MS Excel icon.
Now what should you do if you are still struggling finding the right source program or the extension of the original file? Go for a right click over the file and keep on selecting different programs through Open With option. It means if an XLS file is changed to .Dat file and you try to open it with MS Excel then it will work.
The above case was true because the file was created using an Excel application and all the data in it is appropriate, only the file extension has changed.
One can even go on trying for Windows media player as it would execute it if it happen to be some video file, any MP3 file or maybe any other file of similar nature. So using any of the above methods can bring an answer to your doubt that “What is a dat file”