The Structure of the Registry

There are five primary, or root, branches of the Registry, each containing a specific portion of the information stored therein. These root keys can’t be deleted, renamed, or moved, because they are the basis for the organization of the Registry. They are:


This branch contains the information that comprises your Windows file types. See the discussion of file types in Chapter 4 for details on the structure of most of the entries in this branch. A few special keys here, such as CLSID (short for Class ID), contain “registered” components of Windows and your installed applications. The contents of HKEY_CLASSES_ROOT are generally easy to edit, but it’s best not to mess with anything in the CLSID branch, because almost none of it is in plain English.

This entire branch is a symbolic link,[1] or “mirror,” of HKEY_LOCAL_MACHINE\SOFTWARE\Classes but is displayed separately in this branch for clarity and easy access.


This branch contains a sub-branch for the currently logged-in user, the name of which is a long string of numbers, which will look something like this:


This number is the SID (security identifier), a unique ID for each user on your system. See Chapter 8 for more information on SIDs.

While it may sound like a good idea to edit the contents of this branch, you should instead use the HKEY_CURRENT_USER branch described later, which is a symbolic link, or “mirror,” of this branch. No ...

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