The default location of the Windows registry files depends on the version of Windows being used. On 32-bit versions of Windows, the registry is typically stored in the%SystemRoot%\System32\Config folder, with user-specific settings in the%SystemRoot%\Documents and Settings folder. On 64-bit versions of Windows, the registry is typically stored in the%SystemRoot%\SysWOW64\Config folder, with user-specific settings in the%SystemRoot%\Users folder.
In all versions of Windows, the default location of the registry keys are held in the “HKEY_LOCAL_MACHINE” and “HKEY_CURRENT_USER” roots. Underneath these two roots are a number of sub keys that contain different settings for programs and the Windows Operating System.
Within the “HKEY_LOCAL_MACHINE” root are a number of sub-keys including “Software” and “System”. These keys contain software and hardware information about installed programs, startup information, device drivers and hardware information, including network settings and security settings. There is also a key “SAM” which contains the account information and passwords for all users on the machine.
The “HKEY_CURRENT_USER” root contains the settings for the user currently logged in to Windows. This includes recent document lists, user profile settings, the desktop background and theme and the application settings stored in the Registry.
In addition to the two main roots, there are also two hidden root keys called “HKEY_CLASSES_ROOT” and “HKEY_USERS”. The “HKEY_CLASSES_ROOT” key contains information about file types and associations and the “HKEY_USERS” key contains information about each user account on the computer.
It is important to note that editing the registry directly can cause damage to your system and it is therefore recommended that you use a registry editor such as the one included in Windows or a third-party program to make changes to the registry. It is also recommended that you back up the registry before making any changes.