0 How to open .dat file

.DAT file is nothing but a file containing arbitrary data.  These files are used to store any kind of data by programmers.  It’s not associated with any kind of particular application or a program.  In the case of .DAT files, how to open these files depends on you, it may not be the same program each time.
Some email programs automatically change the file extension on email attachments to .DAT.  So if  any one  sent you a picture and now it’s a .DAT
file, you first need to save it to your computer and then change the file extension to JPG or GIF or PNG or whatever you think it’s supposed to be.  If
they sent you a Word document, change it to .DOC, etc.
We can change the file extension on a file by follow the below steps.
1) First Go to  My Computer,
2) clicking on Tools and then Folder Options.
3) Next click on the View tab and
4) Then scroll down to the option “Hide extensions for known file types” and
UNCHECK it.
Then we can able to see the file extension and change it to another format.
Now simply right-click on the .DAT file and change the file extension to the
desired file format after the dot(.)
You can also try an Integrated Development Environment (IDE)  programmers tool like Winmail.Dat  attachments.  This is an online converter used to open a file easily.
Winmail.Dat Email Attachment
If you have a file named Winmail.dat, this means you have received this file as an attachment in the email and the sender has used Microsoft Outlook,  Outlook Express or MS Exchange Server to send you this mail.