What Is Registry?

The Windows Registry is a hierarchical database that stores configuration settings and options on MS Windows OS. It contains settings for low-level operating system components as well as the applications running on the platform.The Kernel,device drivers,services,SAM(Security Accounts Manager),user interface &third party applications all make use of the registry.

The registry contains two basic elements: keys and values.

Keys are like folders,having sub keys..so on
Values are name/data pairs stored within keys
now coming to HIVES,which are like root Directories,those are

• HKEY_LOCAL_MACHINE or HKLM
• HKEY_CLASSES_ROOT or HKCR
• HKEY_CURRENT_USER or HKCU
• HKEY_USERS or HKU
• HKEY_DYN_DATA (only in Windows 9x/Me, and visible in the Windows Registry Editor)
• HKEY_PERFORMANCE_DATA (only in NT-based versions of Windows, but invisible in the Windows Registry Editor)
• HKEY_CURRENT_CONFIG or HKCC (only in Windows 9x/Me and NT-based versions of Windows)