Opening a .DAT File
How do you open a .DAT file?
I honestly don't know.
Many, many, many programs use .DAT files and, often, these will be in some format specific to the program that created the file. So, it's important that you determine what program created the file.
Once you have determined what program created the file you should then try to use that program with the file. If that doesn't work, you can always try to look into the file and see what is there. This might give you a clue about what to do next.
And, if the file was sent to you by someone then the easiest and fastest way is usually to ask that person.
If that doesn't work...punt.
If the particular file you are interested in is the special file INDEX.DAT then keep reading...
What is INDEX.DAT? INDEX.DAT is a hidden index of the Web sites you visit and the E-mail you send. It is not deleted when you use Windows to clean out temporary Internet files and so is generally available for investigative work even if you think you have cleaned out your browsing history.
INDEX.DAT are generally hidden by Windows so you might only accidently stumble across it. The file itself is generally not hidden under Windows but the directories they are in are often marked both hidden and belong to the system and generally don't show up in an Explorer window even if you have "Show hidden files and folders" checked and "Hide protected operating system files" unchecked in your system preferences. A search for that file name can find the files in Windows but you have to tell the search to specifically look in hidden and system folders. So, you may or may not come across these INDEX.DAT files in your exploration of the hard disk.
Where are they? In several locations and the listing here is not exhaustive but representative...
Under Windows 9x INDEX.DAT files can typically be found in these locations...
Under Windows INDEX.DAT files are found in a much larger number of locations...
How can you manage the INDEX.DAT files? While you can find these files and delete them (if you are worried about them being used to track browsing or E-mail history) the easiest way to manage these files (and other such tracking data) is to use a utility designed for this purpose. In particular, take a look at...
Note: The comments on this page are generally directed toward users of Microsoft browsers and programs. Browsers such as Mozilla Firefox and others generally store their history information in different formats and do not make use of the INDEX.DAT file.