Whenever you visit a website that requires you to enter login details, your Internet Explorer will prompt you "Do you want Internet Explorer to remember the password for xyz website?" If you click 'Yes', then you will not be required to enter the login details again when you visit that site. This removes the hassle of entering the login details every time you visit that site.
Internet Explorer stores all your login details in an encrypted format in the Windows Registry. The passwords can not be seen by anyone in text format or by looking in the registry. If you want to see your saved passwords, you'll have to use a third party program. Such software will search for the saved passwords of IE in the Registry and show them to you in plain text format.
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