The Registry
DEFINITION: The Windows 9x/NT/2000/ME/XP Registry is a complex, unified, system wide, continually referenced during operation database, used for centrally storing, locating, editing and administering system, hardware, software and user configuration information, following a hierarchical structure.
It was introduced to replace the text/ASCII based MS -DOS configuration (.BAT, .SYS) and MS Windows initialization (.INI) files.
Registry Structure
For ease of use, the Registry is divided into five separate structures that represent the Registry database in its entirety. These five groups are known as Keys, and are discussed below:
HKEY_CURRENT_USER
This registry key contains the configuration information for the user that is currently logged in. The users folders, screen colors, and control panel settings are stored here. This information is known as a User Profile.
HKEY_USERS
In windowsNT 3.5x, user profiles were stored locally (by default) in the systemrootsystem32config directory. In NT4.0, they are stored in the systemrootprofiles directory. User-Specific information is kept there, as well as common, system wide user information.
HKEY_LOCAL_MACHINE
This key contains configuration information particular to the computer. This information is stored in the systemrootsystem32config directory as persistent operating system files, with the exception of the volatile hardware key.
HKEY_CLASSES_ROOT
The information stored here is used to open the correct application when a file is opened by using Explorer and for Object Linking and Embedding. It is actually a window that reflects information from the HKEY_LOCAL_MACHINESoftware subkey.
HKEY_CURRENT_CONFIG
The information contained in this key is to configure settings such as the software and device drivers to load or the display resolution to use. This key has a software and system subkeys, which keep track of configuration information.
REG Files
.REG file, which can be in:
* plain text/ASCII format in Windows 95/98/ME and NT/2000/XP or
* binary format in Windows 2000/XP.
Text .REG files can be easily viewed/created/edited by hand using any text/ASCII editor, like Notepad
Their purpose is to add, modify or delete Registry (Sub)Keys and/or Values.
