The windows regedit registry editor is a utility provided by Microsoft that enables you to change information in the windows registry file.

The Windows registry file is a database that contains all the configuration settings in the Windows operating system. It holds the profile for every user who is registered on your PC, information about all internal and external hardware attached to your computer, information about all of the applications installed, and the details on every configuration setting made throughout windows.

Because the Windows registry is an essential part of the operating system, you need to be extremely careful anytime you make a change to it. You should only do any altering if you are proficient and/or have explicit instructions how to alter a component within it.

Below are a few of the things you should know about the windows registry. This will help you avoid the consequences of making a mistake when editing the windows registry.
How the registry is laid out.
The Windows registry is contains five main sections. Theys are called "keys", each containing specific kinds of information about windows. Each section has a nested folder structure containing files which has settings called values. Here are the five main keys in the Windows registry:

• HKEY_CLASSES_ROOT – Contains information about file types.

• HKEY_CURRENT_USER – Contains copies of data stored in HKEY_USERS about the user who is currently logged on.

• HKEY_LOCAL_MACHINE – Represents information about all the hardware and software that is installed on the computer.

• HKEY_USERS – Contains the account information of users installed on your PC.

• HKEY_CURRENT_CONFIG – Contains copies of all the information from all the other root keys that pertain to the currently session.
Backing up the registry.
It is essential that before attempting to change anything in the registry you should make a backup copy of it. You can then restore it to it’s previous state if you make a mistake. There are several ways of backing up the registry.

• Use Windows XP's Backup Utility and select System State.

• Create a Restore Point.

• Launch the Registry Editor, select the key you plan to edit, pull down the File menu, and choose the Export command.
The Regedit Registry Editor.
To view and modify the registry, you can use the Regedit Registry Editor. To startup regedit click on "Start" – "Run" and then type "regedit" in the run text box, then click OK
Searching the registry.

If you know the name of the subkey or value you want to edit in the registry, but you don't know exactly where it's located, you can use the "find" tool. To access it from within the regedit registry Editor, just press [Ctrl]F. When you see the find box, type the name of the subkey or value you want to search for in the box. You can also check the boxes in the "Look At panel" (Keys, Values, or Data) for better targeting of your search.
Using registry favorites.
If you regularly edit the registry, you can use the favorites menu to save yourself time looking for any deeply nested subkeys. The Registry Editor's Favorites menu allows you to bookmark any location you find. When you make a registry change that you may want to return to later, just pull down the Favorites menu and select the "Add To" Favorites command
Cleaning the registry.
After a period of time, the registry can become full of orphaned or corrupt keys and values, This can make the registry inefficient and slow yet still function. There are many registry cleaners out there that perform admirably. One I recommend and use is "Errorfix". This cleaner not only cleans up the registry but provides a lot of other functions as well such as removing unwanted files from your recycle bin.
Monitoring your registry activity.

When you installing new applications, the installation process can make a many changes to the registry. If you would like to keep track of how the registry is changed there is a freeware utility you can use called RegMon. It runs in the background and tracks registry I/O operations. It will then provide a report on the status of those operations, which can come in handy if you need to track problems.

Just remember the regedit registry editor is not to be fooled about with as you can create havoc if not used correctly.