The Windows registry is a database which stores settings and options for the operating system for Microsoft Windows 32-bit versions, 64-bit versions and Windows Mobile.
It contains information and settings for all the hardware, software, users, and preferences of the PC. Whenever a user makes changes to “Control Panel” settings, or file associations, system policies, or installed software, the changes are reflected and stored in the registry.
The registry is actually a big file where a lot of setting can be stored.
This file has been around quite a while and has had different names.
The first windows version that used the windows registry to store settings was windows 3.11 and the registry in that version of windows was called Reg.dat.
In Windows 95 & 98 the registry files are named User.dat and System.dat and are stored in the Windows directory.
Windows ME called the registry files, Classes.dat, User.dat, and System.dat and stored them in the Windows directory.
Finally the newest versions of windows like, Windows NT, 2000, 2003, & XP stores the registry files like this,
The Registry files are stored in %SystemRoot%System32Config: