Wikipedia
The Registry is a hierarchical database that stores low-level settings for the Microsoft Windows operating system and for applications that opt to use the Registry. The kernel, device drivers, services, Security Accounts Manager (SAM), and user interface can all use the Registry. The Registry also allows access to counters for profiling system performance.
In simple terms, The Registry or Windows Registry contains information, settings, options, and other values for programs and hardware installed on all versions …
Windows Registry - Wikipedia, the free encyclopedia