Subtrees of Registry

Understanding the purpose of each subtree can help you locate specific keys and values
in the Registry. The following five subtrees or subtree keys are displayed in the Registry Editor.

HKEY_CLASSES_ROOT Contains software configuration data: object linking and embedding (OLE) and file-class association data. This subtree points to the Classes subkey under HKEY_LOCAL_MACHINE\SOFTWARE.
HKEY_CURRENT_USER Contains data about the current user. Retrieves a copy of each user account used to log on to the computer from the NTUSER.DAT file and stores it in the %systemroot%\Profiles\username key. This subkey points to the same data contained in HKEY_USERS\SID_currently_logged_on_user. This subtree
takes precedence over HKEY_LOCAL_MACHINE for duplicated values.
HKEY_LOCAL_MACHINE Contains all configuration data for the local computer, including hardware and operating system data such as bus type, system memory, device drivers, and startup control data. Applications, device drivers, and the operating system use this data to set the computer configuration. The data in this subtree
remains constant regardless of the user.
HKEY_USERS Contains the .DEFAULT subkey, which holds the system default settings (system default profile) used to display the CTRL+ALT+DELETE logon screen, and the Security Identifier (SID) of the current user.
HKEY_CURRENT_CONFIG Contains data on the active hardware profile extracted from the SOFTWARE and SYSTEM hives. This information is used to configure settings such as the device drivers to load and the display resolution to use.
The HKEY_LOCAL_MACHINE Subtree
HKEY_LOCAL_MACHINE provides a good example of the subtrees in the Registry for two reasons:
■ The structure of all subtrees is similar.
■ HKEY_LOCAL_MACHINE contains information specific to the local computer and is always the same, regardless of the user who is logged on. The HKEY_LOCAL_MACHINE root key has five subkeys.