The Windows Registry stores system configuration details so that Windows looks and behaves just as you want it to. The Registry stores user profile information such as wallpaper, color schemes, and desktop arrangements in a file called user.dat. And it stores hardware- and software-specific details, such as device management and file extension associations, in a file called system.dat.
In many ways, the Registry (Windows 95 and later) replaces functions of win.ini and system.ini from earlier versions of Windows, though these files persist because so many Windows applications refer to them. Registry details can be edited using a program called RegEdit (which ships with Windows 95 and later) and exported to text format as a file with the extension REG.