What is Index.dat file ?

 

Index.dat are files hidden on your computer that contain all of the Web sites that you have ever visited 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.

Purpose:

According to Microsoft, these files are used to cache visited Web sites to help speed up the loading of Web pages in Internet Explorer. Obviously this cannot be the case because when you clear the Temporary Internet Files the “index.dat” files remain behind and continue to grow. If you delete or clear the Temporary Internet Files, there is absolutely no need to index the URL cache because those files no longer exist.

On Windows 2000 and Windows XP there are several “index.dat” files in these locations:

\Documents and Settings\<Username>\Cookies\index.dat
\Documents and Settings\<Username>\Local Settings\History\History.IE5\index.dat
\Documents and Settings<Username>\Local Settings\History\History.IE5\MSHist012001123120020101\index.dat
\Documents and Settings\<Username>\Local Settings\History\History.IE5\MSHist012002010720020114\index.dat
\Documents and Settings\<Username>\Local Internet Files\Content.IE5\index.dat

On Windows Vista and Windows 7 Computer, index.dat files are located :

\Users\<Username>\AppData\Roaming\Microsoft\Windows\Cookies\index.dat
\Users\<Username>\AppData\Roaming\Microsoft\Windows\Cookies\low\index.dat
\Users\<Username>\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\index.dat
C:\Users\<UserName>\AppData\Local\Microsoft\Windows\History\Content.IE5\index.dat

Note : 

Index.dat files are always being used by windows system, you can not delete index.dag files manually, and even you clear Temporary Internet Files on Internet Option of Internet Explorer, it will not delete index.dat files.

Using Tools such Tracks Eraser to delete index.dat files is very easy, simply select the Index.dat on the IE Settings screen.

Tracks Eraser Pro overwrites all the index.dat files with blank characters so that no one can see useful information from these index.dat files.

Note : other Browsers such as Mozilla Firefox, Google Chrome and others generally store their history information in different formats and do not make use of the INDEX.DAT file.