subject: What is the Index.dat File? [print this page] If you use a Windows computer, you are likely familiar with features such as recently used documents and auto complete. These features make it convenient for users to quickly call up information. For example, rather than having to search your hard drive for that document you just created, you can easily call it up thanks to the recently used documents feature. Rather than typing in the complete URL for your favorite Web sites, simply start typing and Windows will automatically fill in the address bar with a matching URL. Windows can call up your recent documents and URLs thanks to a file named index.dat. Why the funny name? The name does give us a clue as to the files purpose. First, the file is an index. Next, the file extension .dat is used by operating systems and applications to indicate data files. So, index.dat is an index of data. In this case, the index contains mostly Web-related data. The index.dat file is used for storing redundant information such as your recently opened documents, search queries, and visited URLs. Your Windows computer likely has several index.dat files as separate ones are created for storing cookies, temporary files, URL content cache, Web history, RSS feeds, and Web-related items. While convenient, if youre concerned about privacy, the index.dat file may give you reason to pause. Thats because if you have an older version of Internet Explorer, when you clear the browsers history, the index.dat file remains. If you dont want your boss to know that you were looking at job openings online, it might make sense to delete the index.dat file after clearing your Web history. However, finding and deleting index.dat files is not easy. First, your computer will have multiple index.dat files, each residing in different folders. Second, these are often hidden files. Third, index.dat files are shared by other components of the Windows operating system, so even if you can find them all, youll likely encounter an access denied message when you try to delete them. Fortunately, according to Ari Pernicks A Bit about WinInets Index.dat MSDN blog post, Internet Explorer version 7 solved this issue by zeroing out entries in the index.dat file once the Delete Files button in Internet Explorers Internet Options dialog box is pressed. Online privacy is a concern to many computer users, even when theyre not doing anything immoral, unethical, or illegal. While the index.dat file isnt necessarily intended to be a secret computer behavior monitoring tool, some users are not comfortable knowing that their entire Web history is stored in an index file. If youre concerned about the index.dat file, upgrade your Web browser to Internet Explorer 7 or 8 and periodically go to Internet Options > Browsing History > Delete and delete your temporary Internet files, cookies, history, form data, passwords, and InPrivate filtering data. Finally, once upgraded, use Internet Explorers InPrivate browsing feature to prevent your visits from being recorded in the first place.
