Think of the Registry in Windows XP Professional as a repository of information on all applications, user profiles, hardware profiles, and even file associations. Its role is to define associations between both software and hardware components in Windows XP. You may be wondering where all this wonderful data resided in Microsoft's operating system structure prior to Windows NT, as in Windows 95. The answer is that previous-generation operating systems relied on a multitude of .INI files to hold the same information that is consolidated into the Registry today. The Registry has been designed to make navigating between the large number of configuration variables possible. So the Registry does away with the many .INI files, and replaces them with a single organized repository of system and environment variables that can be changed on a system-wide level (or just at a specific user level), if necessary. Because the Registry has always been a 32-bit application in Windows NT, long filenames have always been supported. That is a huge improvement over the 8.2 file conventions previously used for .INI files.
And now for some real (old) NT history. The original reason why Microsoft created the Registry was because it needed an approach to handling multiple user profiles on the same system. The old .INI files proved to be cumbersome and difficult to use in completing this task. In fact, the .INI files could not handle defining various characteristics for different user logons. From this confusion in the .INI files, the Registry was created. Since the original development of the Registry, Microsoft has found the concept of a central repository a useful one. Microsoft's COM technology, for example, relies heavily on the Registry for the distributed nature of components.
What's In a Registry?
What immediately comes to mind when someone mentions Registry is the place where gift ideas from the bride and groom are listed. Microsoft's idea of a Registry centers on the concept of creating a tree-like structure that includes keys that define the classes of information in the Registry. Each key can have subkeys as well. Figure 1 shows what the Registry in Windows XP looks like.
Figure 1 Exploring the Windows XP Registry.
In the Registry, the keys have no relation to the keys on your keyboard. The key in the Registry functions more like a pointer or attribute to describe where the item you are looking for resides, relative to other elements in the Registry itself. Think of the keys in the Registry as branches on a tree; each is unique and points in a slightly different direction, as do the keys in the Registry.