As you've seen throughout this book, the Registry lets you change, customize, or manipulate nearly every aspect of Windows XP. So what the heck is it? Actually, it's just a database that contains comprehensive settings for pretty much the whole operating system, as well as settings for the programs you run.
There's just one problem: the Registry is not particularly easy to use. But in many instances, editing the Registry is the only way to customize certain settings. In other cases, you get more options by editing the Registry rather than using menus, buttons, and dialog boxes. (XP contains so many different settings that Microsoft's engineers couldn't reasonably build a graphical interface for you to change all of them.)
You actually change the Registry all the time without knowing it. For example, whenever you adjust a setting using the Control Panel, behind the scenes XP changes the Registry to put that setting into effect.
You edit the Registry using a tool built into XP called the Registry Editor. But before you learn how to use it, you need to grasp how the Registry is organized.
Depending on your XP configuration and the programs you've installed, your Registry may have thousands of settings or tens of thousands of them. The settings are organized into five main Registry sections, called Registry hives . Figure 15-1 shows the structure of the Registry (the hives simply appear as folders), displayed in the Registry Editor.