What is Registry (Registry Explanation)

Question:-How I can know more about Registry?
Answer:-About Registry

Hives
The Registry is split into a number of logical sections, or "hives".[3] Hives are generally named by their Windows API definitions, which all begin "HKEY". They are abbreviated to a three- or four-letter short name starting with "HK" (e.g. HKCU and HKLM).

The HKEY_LOCAL_MACHINE and HKEY_CURRENT_USER nodes have a similar structure to each other; applications typically look up their settings by first checking for them in "HKEY_CURRENT_USER\Software\Vendor's name\Application's name\Version\Setting name", and if the setting is not found looking instead in the same location under the HKEY_LOCAL_MACHINE key. When writing settings back, the reverse approach is used — HKEY_LOCAL_MACHINE is written first, but if that cannot be written to (which is usually the case if the logged-in user is not an administrator), the setting is stored in HKEY_CURRENT_USER instead.

HKEY_CLASSES_ROOT
Abbreviated HKCR, HKEY_CLASSES_ROOT stores information about registered applications, such as Associations from File Extensions and OLE Object Class IDs tying them to the applications used to handle these items. On Windows 2000 and above, HKCR is a compilation of HKCU\Software\Classes and HKLM\Software\Classes. If a given value exists in both of the subkeys above, the one in HKCU\Software\Classes is used.[4]

HKEY_CURRENT_USER
Abbreviated HKCU, HKEY_CURRENT_USER stores settings that are specific to the currently logged-in user. The HKCU key is a link to the subkey of HKEY_USERS that corresponds to the user; the same information is reflected in both locations. On Windows-NT based systems, each user's settings are stored in their own files called NTUSER.DAT and USRCLASS.DAT inside their own documents and settings subfolder.

HKEY_LOCAL_MACHINE
Abbreviated HKLM, HKEY_LOCAL_MACHINE stores settings that are general to all users on the computer. On NT-based versions of Windows, HKLM contains four subkeys, SAM, SECURITY, SOFTWARE and SYSTEM, that are found within their respective files located in the %SystemRoot%\System32\Config folder. A fifth subkey, HARDWARE, is volatile and is created dynamically, and as such is not stored in a file. Information about system hardware drivers and services are located under the SYSTEM subkey, whilst the SOFTWARE subkey contains software and windows settings.

HKEY_USERS
Abbreviated HKU, HKEY_USERS contains subkeys corresponding to the HKEY_CURRENT_USER keys for each user registered on the machine.
[edit] HKEY_CURRENT_CONFIG
Abbreviated HKCC, HKEY_CURRENT_CONFIG contains information gathered at runtime; information stored in this key is not permanently stored on disk, but rather regenerated at boot time.

HKEY_PERFORMANCE_DATA
This key provides runtime information into performance data provided by either the NT kernel itself or other programs that provide performance data. This key is not displayed in the Registry Editor, but it is visible through the registry functions in the Windows API.

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What is Registry- Introduction

Question:-What is Windows Registry?
Answer:-Windows Registry
The Windows registry is a directory which stores settings and options for the operating system for Microsoft Windows 32-bit versions, 64-bit versions and Windows Mobile. It contains information and settings for all the hardware, operating system software, most non-operating system software, users, preferences of the PC, etc. Whenever a user makes changes to Control Panel settings, file associations, system policies, or most installed software, the changes are reflected and stored in the registry. The registry also provides a window into the operation of the kernel, exposing runtime information such as performance counters and currently active hardware. This use of registry mechanism is conceptually similar to the way that Sysfs and procfs expose runtime information through the file system (traditionally viewed as a place for permanent storage), though the information made available by each of them differs tremendously.

The Windows registry was introduced to tidy up the profusion of per-program INI files that had previously been used to store configuration settings for Windows programs.[1] These files tended to be scattered all over the system, which made them difficult to track.


Structure
Keys and Values
The registry contains two basic kinds of elements: keys and values.
Registry Keys are similar to folders - in addition to values, each key can contain subkeys, which may contain further subkeys, and so on. Keys are referenced with a syntax similar to Windows' path names, using backslashes to indicate levels of hierarchy. E.g. HKEY_LOCAL_MACHINE\Software\Microsoft\Windows refers to the subkey "Windows" of the subkey "Microsoft" of the subkey "Software" of the HKEY_LOCAL_MACHINE key.

Registry Values are name/data pairs stored within keys. Values are referenced separately from keys. Value names can contain backslashes which would lead to ambiguities were they referred to like paths. The Windows API functions that query and manipulate registry values take value names separately from the key path and/or handle that identifies the parent key.

The terminology is somewhat misleading, as the values are similar to an associative array, where standard terminology would refer to the name part of the value as a "key". The terms are a holdout from the 16-bit registry in Windows 3, in which keys could not contain arbitrary name/data pairs, but rather contained only one unnamed value (which had to be a string). In this sense, the entire registry was like an associative array where the keys (in both the registry sense and dictionary sense) formed a hierarchy, and the values were all strings. When the 32-bit registry was created, so was the additional capability of creating multiple named values per key, and the meanings of the names were somewhat distorted[2].

There are a number of different types of values:

List of Registry Value Types

0 REG_NONE No type
1 REG_SZ A constant string value
2 REG_EXPAND_SZ An "expandable" string value that can contain environment variables
3 REG_BINARY Binary data (any arbitrary data)
4 REG_DWORD/REG_DWORD_LITTLE_ENDIAN A DWORD value, a 32-bit unsigned integer (numbers between 0 and 4,294,967,295 [232 – 1]) (little-endian)

5 REG_DWORD_BIG_ENDIAN A DWORD value, a 32-bit unsigned integer (numbers between 0 and 4,294,967,295 [232 – 1]) (big-endian)

6 REG_LINK symbolic link (UNICODE)
7 REG_MULTI_SZ A multi-string value, which is an array of strings
8 REG_RESOURCE_LIST Resource list
9 REG_FULL_RESOURCE_DESCRIPTOR Resource descriptor
10 REG_RESOURCE_REQUIREMENTS_LIST Resource Requirements List
11 REG_QWORD/REG_QWORD_LITTLE_ENDIAN A QWORD value, a 64-bit integer (either big- or little-endian, or unspecified)

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Guest article: Computer Error Basics

This is the first guest article here at Bloody Computer! It was written by James Ricketts from Instant Registry Fixes. I hope you enjoy it and find it useful. K

Windows errors can occur at any time due to several reasons. Most of the time, these errors leave us helpless and may even cause us to lose important data and spend large amounts of money on expensive computer repairs.

We end up going through a lot of trouble, when in fact, there are some very simple steps that can easily help prevent these problems from happening in the first place. The top two causes of computer errors are malware and registry errors. Let’s take a look at some of the methods to deal with these problems and fix computer errors.

Keep Your Computer Malware Free

To keep your computer free of errors and other problems, it is essential for all PC users to have anti malware tools installed on their PCs. Primarily, there are three tools that are crucial for all PC users—Anti-virus, Anti-spyware, and Anti-spam.

Antivirus tools help you keep your PC free from malicious programs such as Virus, Trojans, worms, and backdoors. Antispyware tools help prevent and remove spyware and adware programs that steal personal information from your computer and then utilize it to display pop-ads on your PC without your consent. Many adware programs may lead you to dubious Websites or download virus infected programs on your system. Anti-spam tools help you prevent the download of unsolicited, junk e-mail to your system. These tools basically plug-in to your e-mail program such as Microsoft Outlook or Outlook Express and weed out spam mails and help you block them.

There are many anti-malware products available in the market today that incorporate all three tools and provide you with a one point solution to all your malware related problems. However, these products are expensive. And, if you don’t want to spend that much you can look over the Web for freeware and shareware tools and download the ones that have good user reviews and are compatible with your operating system. After you have installed these anti-malware tools on your system, you must be sure to do the following:

• Enable the real-time-protection feature.
• Update them regularly with the latest definition released by their manufacturers.
• Run regular full system scans to keep your system free of malicious information.

Maintain an Error Free Registry

Several Windows errors are generated due to registry problems. Before you learn how to cleanup the registry, you must know what the registry is. The registry is basically a hierarchal database that comprises information related to user preferences, hardware and software configuration and system settings. This is the reason why, there is not a single activity that can be performed on your system without accessing the registry. Registry problems occur when it starts getting filled up with unwanted, obsolete, and erroneous information. Some of the reasons why this data creeps into the registry are:

• Frequent program install and uninstall.
• Incorrect program uninstall.
• Faulty programs and device drivers.
• Malware infections and many more.

This unwanted information causes the registry to grow at an uncontrollable rate and eventually causes registry damage and fragmentation. These registry problems give rise to several computer errors such as runtime errors, dll errors, and driver errors. In severe cases, registry problems may even render your PC unbootable.

Although troublesome, you can easily deal with registry problems with the help of a third-party registry repair tool. There are several tools available on the Internet. You must be sure to look at the features each of them offer, and see what other users have to say about them, in order to download the one that best suits your requirements and is compatible with your operating system.

Some of the tasks you can perform using a registry repair tool are:

• Automatically scan, detect, and remove unwanted and erroneous information from the registry.
• Perform customized searches to look for specific problems and repair them—for instance, to perform DLL repair, you can customize the search for DLL-related problems and resolve them.
• Defrag the registry to reindex its files and reduce its size.
• Backup the registry and easily restore it if your current registry fails.

Regular system maintenance goes a long way in keeping your PC healthy and error-free. In addition to malware and registry scans, you may also use the Disk Cleanup tool to remove junk from your hard disk and use the Disk Defragmenter to consolidate any fragmented files.

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Posted in: Error Messages,Guest article,Protection,Registry