The registry is the heart and soul of MS Windows XP. In my other registry books, I said the same thing about the registry in every version of Windows since MS Windows 95, and by the time you're finished reading this book, I hope you'll agree. The registry contains the configuration data that makes the operating system work. The registry enables developers to organize configuration data in ways that are impossible with other mechanisms, such as INI files. It's behind just about every feature in Windows XP that you think is cool. More importantly, it enables you to customize Windows XP in ways you can't through the user interface.
Windows XP and every application that runs on MS's latest desktop operating system do absolutely nothing without consulting the registry first. When you double-click a file, Windows XP consults the registry to figure out what to do with it. When you install a device, Windows XP assigns resources to the device based on information in the registry and then stores the device's configuration in the registry. When you run an application such as MS Word 2002, the application looks up your preferences in the registry. If you were to monitor the registry during a normal session, you'd see the registry serves up thousands of values within minutes.