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File extension description in German
File extension description in French

File Extension DAT

Files with a file extension DAT are those associated with data. They can be related to anything from text files, graphics, and binary files in programs such as your word processor, graphics programs you use, media player applications or even accumulated data if you are browsing the web with Internet Explorer. A DAT file can be opened by any program which created it and by any text editor you use, such as Microsoft Word or Notepad.

Accessing DAT Files

For a typical PC user, there should be no reason to open a DAT file unless you have received a file in this format from an Exchange server (Winmail.dat) or other location. DAT files are typically used by programmers for inserting code and text for a variety of different PC applications and to discover the purpose of the DAT file as well as its relationship to a program.

The easiest way to open a DAT file is to find out what program created it. You can do this by asking the individual who sent you the file what program they used to create it, such as an email program or other. If this is not possible, you can locate the DAT file by searching for it in the search box located over the Start button. Simply type in the file in the Search box and when Windows Explorer opens and displays the file, double click on it to see if one of your programs opens it by default.

If the above process is unsuccessful, you can view the file to learn what program created it by setting up a shortcut to Notepad. If you are using Windows 7, click on the Start button on the main toolbar of your Desktop and then enter shell:sendto in the Search box and hit the Enter key. When Windows Explorer opens, right click on an open space somewhere on the inside of the window and click on New from the drop-down menu and choose Shortcut. In the Shortcut window, enter Notepad.exe and then name the file Notepad and close the window.

Once you have created the shortcut, you can now go into Windows Explorer, find the DAT file you wish to examine and right click on it. When the drop-down menu appears, click on Send To and then choose Notepad from the submenu. This will automatically open the DAT file in Notepad so you can find out what program created it.

Index.dat Files

If you are wondering about the Index.dat file, this is a common file in the Internet Explorer browser that tracks the websites you visit online, searches you have entered in your browser, and files you have opened while browsing the Internet.

The Index.dat file is different than your browser history and Internet temp files, since it helps you to complete the typing of URLs you frequently visit and website forms you fill out online. The issue with this type of the DAT format is that it remains in the Windows operating system despite the fact you may have disabled the Auto Complete feature in your browser. The Index.dat file also does not appear in Windows Explorer if you try to search for it to open and view the contents. If you delete your browsing history and temporary Internet files, the Index.dat file remains intact on your PC.

The process for opening or deleting the Index.dat file is rather involved and requires an MS-DOS boot disk or software which is specifically designed to locate and open the Index.dat files or delete this type files altogether.