REGISTRYThe Registry is the heart and soul of Microsoft Windows XP and can be called as “building block of OS” . Simply put, the registry is nothing more than your computer's settings.Lineage of registryMS−DOS Every application that ran on MS−DOS was responsible for managing its own settings. Microsoft Windows 3.0 This version provided INI files for storing settings. Every application had its own INI files.Windows 3.1 Registry was introduced as a tool for storing OLE (object linking and embedding) settings. And Windows 95 & Windows NT 3.5 expanded the registry to the configuration database that Windows XP uses now. Some of its main functionsThe registry contains the configuration data that makes the operating system work.It enables you to customize Windows XP in ways you can't through the user interface.The registry enables developers to organize configuration data in ways that are impossible with INI files.Windows XP and every application that runs on Microsoft's latest desktop operating system do absolutely nothing without consulting the registry first.For each and every double−click , Windows XP consults the registry to figure out what to do with it. When a device is installed , Windows XP assigns resources to the device based on information in the registry and then stores the device's configuration in the registry. When an application such as Microsoft Word 2002 is being run , the application looks up your preferences in the registry. This built-in facility of Microsoft Windows Xp is used by,Power users IT professionalsRegistry is a great paradox .On the one hand, it's the central place for all of Windows XP's configuration data. On the other hand, the fact that the registry is so critical, also makes it one of the operating system's weaknesses. If the registry fails, Windows XP fails.Getting started1. Click on Start button 2. Then on Run from menu 3. Run dialogue box will appear 4.In the Open text box type the command “regedit” or “regedt32.exe”Structure of registryThe structure of Windows XP's registry is so similar to the structure of its file system In the editor's left pane, which is called the key pane, just as Windows Explorer's left pane. Each folder in the key pane is a registry key. In the editor's right pane, which is called the value pane, you see a key's values. Basics of Registry KeysKeys are so similar to folders (Registry Editor even uses the same icon for keys as Windows Explorer uses for folders) that they have the same naming rules. A key's name is limited to 256 Unicode characters, and you can use any ASCII character in the name other than a backslash (), asterisk (*), and question mark (?). In addition, Windows XP reserves all names that begin with a period for its own use. Root keysHKEY_CLASSES_ROOTHKEY_CURRENT_USERHKEY_LOCAL_MACHINEHKEY_USERSHKEY_CURRENT_CONFIG Values-Each key contains one or more values. A value's name is similar to a file's name. A value's type is similar to a file's extension, which indicates its type.A value's data is similar to the file's actual contents. Parts of a valueNameEvery value has a name. up to 256 Unicode characters except for the backslash (), asterisk (*), and question mark (?), with Windows XP reserving all names that begin with a period. TypeEach value's type determines the type of data that it contains. For example, a REG_DWORD value contains a double-word number, and a REG_SZ value contains a string.DataEach value can be empty or null or can contain data. A value's data can be a maximum of 32,767 bytes, but the practical limit is 2 KB.Default valueDefault value is almost always a string type.In most cases, the default value is null.Types of dataWindows XP supports the following types of data in the registry. As you look through this list, realize that REG_BINARY, REG_DWORD, and REG_SZ account for the vast majority of all the settings in the registry:REG_BINARYREG_DWORDREG_DWORD_BIG_ENDIANREG_DWORD_LITTLE_ENDIANREG_EXPAND_SZREG_FULL_RESOURCE_DESCRIPTORREG_LINKREG_NONEREG_QWORDREG_QWORD_BIG_ENDIANREG_QWORD_LITTLE_ENDIANREG_RESOURCE_LISTREG_RESOURCE_REQUIREMENTS_LISTREG_SZHKEY_CURRENT_USERContains the root of the configuration information for the user who is currently logged on. The users folders, screen colors and control panel settings are stored here. This information is referred to as a users profile. HKEY_USERSContains the root of all user profiles on the computer. HKEY_CURRENT_USER is a sub-key of HKEY_USERS. HKEY_LOCAL_MACHINEContains the configuration particular to the computer (for any user). HKEY_CLASSES_ROOTIt is sub-key of HKEY_LOCAL_MACHINESOFTWARE. The information stored here ensures that the correct program opens when you open a file by using windows explorer.HKEY_CURRENT_CONFIGContains information about the hardware profile used by the local computer at system startup. Using registry editor and customizing your computer Disable right click Disable Run from start menuDisable Volume Disable Control panelCreating a System keyDisable Appearance tabDisable Settings tabDisable Screen saver tabDisable Password changing Registry management toolsHundreds of third−party and shareware registry tools are available. You learn about many of them throughout this book. Some tools I use more often than others, though, and here's an introduction to them:Registry EditorThis is the primary tool you use to edit settings in the registry.Console Registry Tool for Windows (Reg.exe)This command−line registry tool supports most of the capabilities of Registry Editor. The significance of this tool is that it allows you to script edits in batch files. WinDiff This tool comes with the Windows XP Support Tools, which you install from SupportTools on the Windows XP CD. Most of the Windows 2000 Resource Kit tools still work well in Windows XP, and you can download many of them from Microsoft's Web site at http://www.microsoft.com/windows2000/techinfo/reskit/tools/default.asp.