• It only hides, but doesn't really erase the data from the files you've deleted or emptied from the recycle bin. These files can easily be recovered by scanning your unused free space with widely available data recovery software.
• It stores sensitive user-specific information such as user names and passwords used to access secure web pages in files called 'cookies'. The private data cookies may store can represent a security risk.
• It downloads and stores files from every website you've visited in its cache (temporary internet files folder), including pictures, videos, audio, scripts, mp3s, and other data.
• It stores a record of every web site you've previously visited in a locked hidden file called 'index.dat', viewable by hitting 'Ctrl-H' from within Internet Explorer.
• It saves a list of all URL's you've previously typed in the address bar of Internet Explorer.
• It tracks every document you've recently opened on your computer, such as Word, Excel, Notepad, and other documents or files.
• It stores every command previously typed into the 'Start/Run...' control. This list can provide information about recently run programs, recently browsed folders, or recently visited web sites.
• Loaning, selling, or donating your computer without properly destroying sensitive data first is an invitation to identity theft, and allows thieves to easily access your personal information.