The Registry has a hierarchal structure, like the directories on your hard disk.
Each branch (denoted by a folder icon in the Registry Editor, see below) is called a Key.
Each key can contain other keys, as well as Values.
Each value contains the actual information stored in the Registry.
There are three types of values; String, Binary, and DWORD - the use of these depends upon the context.
There are six main branches, each containing a specific portion of the information stored in the Registry. They are as follows:

HKEY_CLASSES_ROOT - this branch contains all of your file types as well as OLE information for all your OLE-aware applications.

HKEY_CURRENT_USER - this branch points to the part of HKEY_USERS appropriate for the current user.

HKEY_LOCAL_MACHINE - this branch contains information about all of the hardware and software installed on your computer.
Since you can specify multiple hardware configurations, the current hardware configuration is specified in HKEY_CURRENT_CONFIG. HKEY_USERS - this branch contains certain preferences (such as colors and control panel settings) for each of the users of the computer.
Although Windows 98 can be configured for multiple users (the user currently logged in is specified in HKEY_CURRENT_USER), there is usually only one user, called default.

HKEY_CURRENT_CONFIG - this branch points to the part of HKEY_LOCAL_MACHINE appropriate for the current hardware configuration.

HKEY_DYN_DATA - this branch points to the part of HKEY_LOCAL_MACHINE, for use with the Plug-&-Play feature of Windows 98.

The Registry Editor (REGEDIT.EXE) is included with Windows 98 to enable you to view and edit the contents of the Registry.
When you open the Registry Editor, you'll see a window divided into two panes.
The left side shows a tree with folders (see Structure of the Registry below), and the right side shows the contents (values) of the currently selected folder.
To expand a certain branch, click on the little plus sign [+] to the left of any folder, or just double-click on the folder.
To display the contents of a key (folder), just click the desired key, and look at the values listed on the right side.
You can add a new key or value by selecting New from the Edit menu.
You can rename any value and almost any key with the same method used to rename files; right-click on an object and click rename, or click on it twice (slowly), or just press F2 on the keyboard.
Lastly, you can delete a key or value by clicking on it, and pressing Delete on the keyboard, or by right-clicking on it, and choosing Delete.

Importing, Exporting, and Applying Patches Although you can edit the Registry with the Registry Editor (see above), you can also make changes by using Registry patches.
A Registry patch is a simple text file with the .REG extension that contains one or more keys or values.
If you double-click on a .REG file, the patch is applied to the registry.
This is a good way to share or back up small portions of the registry for use on your own computer, or someone else's, because it's much simpler and less dangerous than manually editing the Registry.
You can create a Registry patch by opening the Registry Editor, selecting a branch, and choosing Export from the File menu.
Then, specify a filename, and press OK.
You can then view the Registry patch file by opening it in Notepad (right-click on it and select Edit).
Again, just double-click on a Registry patch file (or use Import in the Registry Editor's File menu) to apply it to the registry.