What is an index.dat?
An index.dat file is a hidden file that contains a record of every web site address you have ever visited and holds information on all your Internet activities, yes including emails sent and received through Outlook or Outlook Express One of these files can be located and viewed by Windows Explorer but none can be deleted using either Windows Explorer According to Microsoft these files are used to help speed up loading of web pages in Internet Explorer. This doesn't appear to be case because when you delete Temporary Internet Files "index.dat" files remain behind and continue to grow. If you delete or clear Temporary Internet Files then there is no need to index URL cache because files no longer exist.
Where are my index.dat files located?
On Windows 95 and 98 computers files are located in following locations:
C:WINDOWSCookies C:WINDOWSHistoryHistory.IE5*.* C:WINDOWSTemporary Internet FilesContent.IE5*.*
In Windows 2000 and Windows XP files are located in following locations:
Documents and SettingsCookiesindex.dat Documents and SettingsLocal SettingsHistoryHistory.IE5index.dat Documents and SettingsLocal SettingsHistoryHistory.IE5 MSHist012001123120020101index.dat
Documents and SettingsLocal SettingsHistoryHistory.IE5 MSHist012002010720020114index.dat
Documents and SettingsLocal Internet FilesContent.IE5index.dat