What's: Registry
The registry is an important component of Windows. All current system settings are listed here as well as all installed software.

The registry has to be handled carefully, a false change is able to cause serious problems such as the computer might not start anymore and a program might not recognized any longer. Since all installed programs are listed in the registry, it is not enough to delete software under Windows, it has to be removed out of the registry with the according deinstallation program or via the Windows function in System Control / Software / "Add and Remove".

IF you like to adjust registry settings manually start the registry editor "regedit" (in the start menu). Enter here "regedit" as command.
Registry im deutschen Lexikon
Registry in het nederlandse encyclopedie