What is Registry key in Windows 10? and why is important?

I am new to the system admin thing I have joined as a junior system admin engineer in one of the small company in my locals. I was studying my senior work he has mentioned some many things related to Windows Registry and in fact he is using the Registry option to control most of the Windows 10 feature in my office.

I would like to know more about Windows Registry. What is Windows Registry? Why is more important in Windows 10? What happen if I mess up with Windows Registry? etc etc.,

Any clear explanation would be more helpful. Thanks for reading and hoping to get better answer’s



What is Windows Registry Key:

The Windows 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, and user interface can all use the registry. The registry also allows access to counters for profiling system performance.

In other words, the registry or Windows Registry contains information, settings, options, and other values for programs and hardware installed on all versions of Microsoft Windows operating systems. For example, when a program is installed, a new subkey containing settings such as a program’s location, its version, and how to start the program, are all added to the Windows Registry.

Why Registry Key are very Important:

The registry very is important because it stores vital information about your Windows system and its configuration, as well as info about all application programs installed on your computer.

Whenever you add and remove software, change your settings, add new devices, or upgrade your system, your registry is changed.


A registry hive is a group of keys, subkeys, and values in the registry that has a set of supporting files that contain backups of its data. The supporting files for all hives except HKEY_CURRENT_USER are in the %SystemRoot%\System32\Config folder on Windows NT 4.0, Windows 2000, Windows XP, Windows Server 2003, and Windows Vista. The supporting files for HKEY_CURRENT_USER are in the %SystemRoot%\Profiles\Username folder. The file name extensions of the files in these folders indicate the type of data that they contain. Also, the lack of an extension may sometimes indicate the type of data that they contain.

Registry hive Supporting files
HKEY_LOCAL_MACHINE\SAM Sam, Sam.log, Sam.sav
HKEY_LOCAL_MACHINE\Security Security, Security.log, Security.sav
HKEY_LOCAL_MACHINE\Software Software, Software.log, Software.sav
HKEY_LOCAL_MACHINE\System System, System.alt, System.log, System.sav
HKEY_CURRENT_CONFIG System, System.alt, System.log, System.sav, Ntuser.dat, Ntuser.dat.log
HKEY_USERS\DEFAULT Default, Default.log, Default.sav

In Windows 98, the registry files are named User.dat and System.dat. In Windows Millennium Edition, the registry files are named Classes.dat, User.dat, and System.dat.